I removed a ds aug from my shoulders today to add a 1k hp aug. I put the shoulders in the aug pool then the hp aug. They did not combine and when I picked them up and put them back in my inventory they both poofed. 2.5k hp gone.
I did this with Mil's 3.0 =X if an item already has an aug in it don put that item and another aug into the aug pool and hit combine...it will do nothing at first but when you take both items out and put them somewhere it will delete them.
I had actually just removed an aug from it, (ds aug) put the aug in a bag, (still there) and then put the de-auged shoulder item back into the aug pool. Then I put the hp aug in the aug pool and hit done. Nothing happened, I looked at my lag bar to see if I was going ld, (wasn't) then removed the aug from the aug pool and put it in my inventory. I figured it poofed because it went into thee shoulder item. I then removed the shoulder item from the aug pool and put it into my shoulder slot. It poofed as well.
That is verbatim what I did.