yes its ok but its also a waste since going the same line, same ship also... let you other bo go on different line so you could try the ships that on the other line

thanks for answering
so basically I just keep going through the bb line but when i get to choose between some different ships, like the svetlana or the bogatyr i choose one with each bo? same with gangut and izmail?
problem there would be if i didnt like one of the other lines i still would have to lvl both bos...
also.. am i supposed to keep lvling both BOs for ever or should i change to lvling only one when tehres enough lvl difference between my BO and my gunners?

Yes, use different ship lines. Buy the PBB when you get to the lvl and use both BOs on it.