I'm guessing... dual male RCA to stereo phono plug?
or... female phono jack to going to dual rca's?
(I recommend the former, as it forgoes a unnecessary connection)
Either way, you could easily DIY one following
this guide(same as the mini-to-rca), or get someone on the forums to make one for you.
Star quad for very acceptable quality at a good price.
I can't think of a lot of applications for 1/4 trs to dual rca's.. so I doubt there are a lot of commercial offerings.