No, you only need to insert a sample bank once. If you want to use the sample bank in multiple levels, select the level to use under Level Select, and the bank to use just below that. Just select the bank number that the first level (the one with the bank you want to use multiple times) uses.
Alternately, if you're willing to wait hopefully just a bit longer, just use AddmusicK when it's released. It handles all this messy sample bank business automatically.
I should get a new layout.
Probably won't, though.