diff --git a/src/handle_request.js b/src/handle_request.js
index ac6a8f7..3521dc0 100644
--- a/src/handle_request.js
+++ b/src/handle_request.js
@@ -28,14 +28,14 @@ function handleRequest(mockAdapter, resolve, reject, config) {
   );
 
   if (handler) {
-    utils.purgeIfReplyOnce(mockAdapter, handler);
-
-    if (handler.length === 2) {
-      // passThrough handler
+    if (handler.length === 2) { // passThrough handler
       // tell axios to use the original adapter instead of our mock, fixes #35
       config.adapter = mockAdapter.originalAdapter;
       mockAdapter.axiosInstance.request(config).then(resolve, reject);
     } else if (!(handler[3] instanceof Function)) {
+      if (handler.length === 7) {
+        utils.purgeIfReplyOnce(mockAdapter, handler);
+      }
       utils.settle(
         resolve,
         reject,
diff --git a/src/index.js b/src/index.js
index a907416..33bd327 100644
--- a/src/index.js
+++ b/src/index.js
@@ -1,5 +1,7 @@
 'use strict';
 
+var deepEqual = require('deep-equal');
+
 var handleRequest = require('./handle_request');
 
 var VERBS = ['get', 'post', 'head', 'delete', 'patch', 'put', 'options'];
@@ -24,7 +26,6 @@ function reset() {
     accumulator[verb] = [];
     return accumulator;
   }, {});
-  this.replyOnceHandlers = [];
 }
 
 function MockAdapter(axiosInstance, options) {
@@ -64,9 +65,8 @@ VERBS.concat('any').forEach(function(method) {
       reply: reply,
 
       replyOnce: function replyOnce(code, response, headers) {
-        var handler = [matcher, body, requestHeaders, code, response, headers];
+        var handler = [matcher, body, requestHeaders, code, response, headers, true];
         addHandler(method, _this.handlers, handler);
-        _this.replyOnceHandlers.push(handler);
         return _this;
       },
 
@@ -96,13 +96,38 @@ VERBS.concat('any').forEach(function(method) {
   };
 });
 
+function findInHandlers(method, handlers, handler) {
+  var index = -1;
+  for (var i = 0; i < handlers[method].length; i += 1) {
+    var item = handlers[method][i];
+    var isReplyOnce = item.length === 7;
+    var comparePaths = item[0] instanceof RegExp && handler[0] instanceof RegExp
+      ? String(item[0]) === String(handler[0])
+      : item[0] === handler[0];
+    var isSame = (
+      comparePaths &&
+      deepEqual(item[1], handler[1], { strict: true }) &&
+      deepEqual(item[2], handler[2], { strict: true })
+    );
+    if (isSame && !isReplyOnce) {
+      index =  i;
+    }
+  }
+  return index;
+}
+
 function addHandler(method, handlers, handler) {
   if (method === 'any') {
     VERBS.forEach(function(verb) {
       handlers[verb].push(handler);
     });
   } else {
-    handlers[method].push(handler);
+    var indexOfExistingHandler = findInHandlers(method, handlers, handler);
+    if (indexOfExistingHandler > -1 && handler.length < 7) {
+      handlers[method].splice(indexOfExistingHandler, 1, handler);
+    } else {
+      handlers[method].push(handler);
+    }
   }
 }
 
diff --git a/src/utils.js b/src/utils.js
index b97af01..5420cc1 100644
--- a/src/utils.js
+++ b/src/utils.js
@@ -75,17 +75,12 @@ function isBodyMatching(body, requiredBody) {
 }
 
 function purgeIfReplyOnce(mock, handler) {
-  var index = mock.replyOnceHandlers.indexOf(handler);
-  if (index > -1) {
-    mock.replyOnceHandlers.splice(index, 1);
-
-    Object.keys(mock.handlers).forEach(function(key) {
-      index = mock.handlers[key].indexOf(handler);
-      if (index > -1) {
-        mock.handlers[key].splice(index, 1);
-      }
-    });
-  }
+  Object.keys(mock.handlers).forEach(function(key) {
+    var index = mock.handlers[key].indexOf(handler);
+    if (index > -1) {
+      mock.handlers[key].splice(index, 1);
+    }
+  });
 }
 
 function settle(resolve, reject, response, delay) {
diff --git a/test/basics.spec.js b/test/basics.spec.js
index f0e1dad..06d5fad 100644
--- a/test/basics.spec.js
+++ b/test/basics.spec.js
@@ -532,4 +532,143 @@ describe('MockAdapter basics', function() {
         expect(data[0].bar).to.equal(123);
       });
   });
+
+  it('should overwrite existing mock', function() {
+    mock.onGet('/').reply(500);
+    mock.onGet('/').reply(200);
+
+    return instance
+      .get('/')
+      .then(function(response) {
+        expect(response.status).to.equal(200);
+      });
+  });
+
+  it('should not add duplicate handlers', function() {
+    mock.onGet('/').replyOnce(312);
+    mock.onGet('/').reply(200);
+    mock.onGet('/1').reply(200);
+    mock.onGet('/2').reply(200);
+    mock.onGet('/3').replyOnce(300);
+    mock.onGet('/3').reply(200);
+    mock.onGet('/4').reply(200);
+
+    expect(mock.handlers['get'].length).to.equal(7);
+  });
+
+  it('supports chaining on same path with different params', function() {
+    mock
+      .onGet('/users', { params: { searchText: 'John' } }).reply(200, { id: 1 })
+      .onGet('/users', { params: { searchText: 'James' } }).reply(200, { id: 2 })
+      .onGet('/users', { params: { searchText: 'Jake' } }).reply(200, { id: 3 })
+      .onGet('/users', { params: { searchText: 'Jackie' } }).reply(200, { id: 4 });
+
+    return instance.get('/users', { params: { searchText: 'John' } })
+      .then(function(response) {
+        expect(response.data.id).to.equal(1);
+        return instance.get('/users', { params: { searchText: 'James' } });
+      })
+      .then(function(response) {
+        expect(response.data.id).to.equal(2);
+        return instance.get('/users', { params: { searchText: 'Jake' } });
+      })
+      .then(function(response) {
+        expect(response.data.id).to.equal(3);
+        return instance.get('/users', { params: { searchText: 'Jackie' } });
+      })
+      .then(function(response) {
+        expect(response.data.id).to.equal(4);
+      });
+  });
+
+  it('should overwrite replys', function() {
+    mock.onGet('/').reply(500);
+    mock.onGet('/').reply(200);
+    mock.onGet('/').reply(401);
+
+    return instance.get('/')
+      .catch(function(error) {
+        expect(mock.handlers['get'].length).to.equal(1);
+        expect(error.response.status).to.equal(401);
+      });
+  });
+
+  it('should overwrite replys using RegEx', function() {
+    mock.onGet(/foo\/bar/).reply(500);
+    mock.onGet(/foo\/bar/).reply(200);
+    mock.onGet(/foo\/baz\/.+/).reply(200);
+
+    return instance.get('/foo/bar')
+      .then(function(response) {
+        expect(mock.handlers['get'].length).to.equal(2);
+        expect(response.status).to.equal(200);
+        return instance.get('/foo/baz/56');
+      })
+      .then(function(response) {
+        expect(response.status).to.equal(200);
+      });
+  });
+
+  it('should allow overwriting only on reply if replyOnce was used first', function() {
+    var counter = 0;
+    mock.onGet('/').replyOnce(500);
+    mock.onGet('/').reply(200);
+    mock.onGet('/').reply(401);
+
+    return instance.get('/')
+      .catch(function(error) {
+        expect(error.response.status).to.equal(500);
+        counter += 1;
+        return instance.get('/');
+      })
+      .catch(function(error) {
+        expect(error.response.status).to.equal(401);
+        counter += 1;
+      })
+      .then(function() {
+        expect(counter).to.equal(2);
+      });
+  });
+
+  it('should not allow overwriting only on reply if replyOnce wasn\'t used first', function() {
+    var counter = 0;
+    mock.onGet('/').reply(200);
+    mock.onGet('/').reply(401);
+    mock.onGet('/').replyOnce(500);
+    mock.onGet('/').reply(500);
+
+    return instance.get('/')
+      .catch(function(error) {
+        expect(error.response.status).to.equal(500);
+        counter += 1;
+        return instance.get('/');
+      })
+      .catch(function(error) {
+        expect(error.response.status).to.equal(500);
+        counter += 1;
+      })
+      .then(function() {
+        expect(counter).to.equal(2);
+      });
+  });
+  it('allows overwriting mocks with parameters', function() {
+    mock
+      .onGet('/users', { params: { searchText: 'John' } })
+      .reply(500)
+      .onGet('/users', { params: { searchText: 'John' } })
+      .reply(200, { id: 1 });
+
+    return instance.get('/users', { params: { searchText: 'John' } })
+      .then(function(response) {
+        expect(response.status).to.equal(200);
+      });
+  });
+
+  it.only('allows overwriting mocks with headers', function() {
+    mock.onGet('/', {}, { 'Accept-Charset': 'utf-8' }).reply(500);
+    mock.onGet('/', {}, { 'Accept-Charset': 'utf-8' }).reply(200);
+
+    expect(mock.handlers['get'].length).to.equal(1);
+    expect(mock.handlers['get'][0][3]).to.equal(200);
+  });
 });