Create 1 NGUI atlas , which has more than 1 PNG's

Hope you are doing well. We are using NGUI(do not drop rocks on me :D :D ) with Unity, and I have a question. Is There a way to make an atlas that has 2 or more png's ?

Other Atlas packers has that option, so I can make for example 2x 2048x2048 PNG's, which point to the same .atlas file. But I can't find something like this in NGUI atlas maker.

Generally, now I have an Atlas which size is 4096x2048. I want to split it into 2x 2048x2048 atlases, but with the same reference, as I don't want to make 2 separate atlases and deep into finding and changing assets manually.

Thanks