The material should meet in the pontic, I don't remember ever having a demarcation line where the material met. This is what Ivoclar recommends...although I've seen techs get away with individual sprues and a 6ga runner bar as well...
Have had it happen, I put one on each as if they were singles to try to avoid this and attach direct to sprue former. Never had any issues spruing this way. Make sure to use a 200g ring even though it may fit with a single ingot in a 100g.
If it was me. I would use a thick gauge wax runner for a bar. Then some thinner wax sprues to the the lingual. Then I would proceed to pray to the" Emax Gods" for a successful press.
O.K. here is what I ended up with. I had a demarcation line in one of them. It didn't matter because I ended up doing a little overlay. Tough case to do much with. The Dr. is going to to bond the facials of 6 and 11..