As an error state, you use somewhere an object with more than one property with the same name. Sort of:
var obj= { property1: 0, property2: 1, property1: 2 };
Printing the top object results in:
{ property1: 2, property2: 1 }
Also, a little distorted when the stack overflows, you can find a more detailed answer why this error is displayed in Internet Explorer
What is the purpose of resolving duplicate property names?
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