I had this weird dream last night, and somehow i was handed a bearing. no normal bearing though, it was like a reverse konkave, but it had one little slight konkave near each edge and it got me thinking. Two strings, one yo-yo? O.o :
;D 
I don’t know about 2 strings one yoyo. Sorta reminds me of astrojax kind of stuff without the throw/recall bit. But, I could see it being helpful for 3A to help keep the strings apart a bit. However, not sure how helpful this would be.
2 strings one yoyo’s been done. it’s one of those styles that aren’t particularly common though.
they have a list of all the styles of play on yoyo wiki.
I tried attaching two strings thinking there could be new tricks… Turns out to be very limiting…
Rei Iwakura worlds AP 2010