diff --git a/.eslintrc b/.eslintrc
index 093ed358b6f..9404630b5bc 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -22,7 +22,6 @@
     "no-trailing-spaces": [2],
     "no-multiple-empty-lines": [2, {"max": 2, "maxEOF": 0}],
     "eol-last": [2],
-    "linebreak-style": [2, "unix"],
     "indent": [2, 4, {"SwitchCase": 1}],
     "max-len": [0, 80],
     "brace-style": [0, "stroustrup", {"allowSingleLine": true}],
diff --git a/src/plot_api/plot_api.js b/src/plot_api/plot_api.js
index bd9f22f8fe8..1a5bd8d1fc0 100644
--- a/src/plot_api/plot_api.js
+++ b/src/plot_api/plot_api.js
@@ -633,8 +633,7 @@ function checkMoveTracesArgs(gd, currentIndices, newIndices) {
  * @param newIndices
  */
 function checkAddTracesArgs(gd, traces, newIndices) {
-    var i,
-        value;
+    var i, value;
 
     // check that gd has attribute 'data' and 'data' is array
     if(!Array.isArray(gd.data)) {
@@ -956,10 +955,16 @@ Plotly.addTraces = function addTraces(gd, traces, newIndices) {
     if(!Array.isArray(traces)) {
         traces = [traces];
     }
+
+    // make sure traces do not repeat existing ones
+    traces = traces.map(function(trace) {
+        return Lib.extendFlat({}, trace);
+    });
+
     helpers.cleanData(traces, gd.data);
 
     // add the traces to gd.data (no redrawing yet!)
-    for(i = 0; i < traces.length; i += 1) {
+    for(i = 0; i < traces.length; i++) {
         gd.data.push(traces[i]);
     }
 
diff --git a/test/jasmine/tests/plot_api_test.js b/test/jasmine/tests/plot_api_test.js
index c4d99ac8846..80acfbb1b7e 100644
--- a/test/jasmine/tests/plot_api_test.js
+++ b/test/jasmine/tests/plot_api_test.js
@@ -414,7 +414,6 @@ describe('Test plot api', function() {
 
             // make sure we didn't muck with gd.data if things failed!
             expect(gd).toEqual(expected);
-
         });
 
         it('should throw an error when traces and newIndices arrays are unequal', function() {
@@ -454,7 +453,6 @@ describe('Test plot api', function() {
             expect(gd.data[3].uid).toBeDefined();
             expect(PlotlyInternal.redraw).not.toHaveBeenCalled();
             expect(PlotlyInternal.moveTraces).toHaveBeenCalledWith(gd, [-2, -1], [1, 3]);
-
         });
 
         it('should work when newIndices has negative indices', function() {
@@ -465,7 +463,6 @@ describe('Test plot api', function() {
             expect(gd.data[3].uid).toBeDefined();
             expect(PlotlyInternal.redraw).not.toHaveBeenCalled();
             expect(PlotlyInternal.moveTraces).toHaveBeenCalledWith(gd, [-2, -1], [-3, -1]);
-
         });
 
         it('should work when newIndices is an integer', function() {
@@ -474,7 +471,21 @@ describe('Test plot api', function() {
             expect(gd.data[2].uid).toBeDefined();
             expect(PlotlyInternal.redraw).not.toHaveBeenCalled();
             expect(PlotlyInternal.moveTraces).toHaveBeenCalledWith(gd, [-1], [0]);
+        });
+
+        it('should work when adding an existing trace', function() {
+            Plotly.addTraces(gd, gd.data[0]);
+
+            expect(gd.data.length).toEqual(3);
+            expect(gd.data[0]).not.toBe(gd.data[2]);
+        });
+
+        it('should work when duplicating the existing data', function() {
+            Plotly.addTraces(gd, gd.data);
 
+            expect(gd.data.length).toEqual(4);
+            expect(gd.data[0]).not.toBe(gd.data[2]);
+            expect(gd.data[1]).not.toBe(gd.data[3]);
         });
     });