Merging two tubes made with the Sweep tool

I would like to create a „Y“ shaped tube. So I drew a spine, mirrored it and drew two concentric circles in the z—axis. Sweeping and then having both Parts of the „Y“
Then I merged them in freeform. But now the tubes are filled in the merged areas. I thought, substracting them from each other would be a good idea, but it had not the wanted effect.
Any suggestions?
Here is the link to the project:

Use the inner circle and sweep it as a solid piece, (on the spline) then subtract it from the the other.
Or, hide one of them, create a new pice that cover half the tube then subtract it , then do the same to the first one on the opposite side, then merge them together.
Or, you can do it the same way you did before but use the intersect tool first, ther you have a new piece that you can merge in to were its missing substance, delete the junk first.