Retain duplicate declarations in an array

I noticed, while parsing my custom css, that duplicate declarations were being overwritten with the last declaration. In my case, I wanted to handle the duplicates independently.

So:

    #test1 {
      color: blue;
      color: red;
    }

now results in:

    {
     declarations: { color: ["blue", "red"]  },
     selector: "#test1",
     type: "style"
    }