2x8-10-12

I have a question if anyone can help me. My plans call for a "2x8 to 2x12" joist hanger SGL and "2x8 to 2x12" DBL. I found the single hangers fine but I cannot find the double hangers anywhere. The question I have is can I just buy a 2x12 joist hanger or does the "2x8 to 2x12" mean something...