There’s no problems with getting another bachelor (there are very few rules beyond The School Wants Your Money and they’re more than willing to give you as many degrees as you give them money), but if you can find a design master’s program that will accept you based on your current bachelor, I’d recommend that. Why? One, the masters program is much shorter than another bachelor program. Two, I would say a bachelor/master combo has more value than two bachelors, but this is really subjective and what matters most is what your future employer values. As for applying to a Master’s program with an unrelated bachelor degree, the best way to find out is to ask the program you apply to. Some will be lenient, some will not. Some will accept your bachelor as the credential, some will require you to have one from their school even. Since all schools have their own policy, the only way to find out for sure is to make a list and call them up on the phone one by one, old school style. In general though, I would recommend you reflect on what you want to do in life, and find out what training you need to get yourself to your goal. After all, you can’t stay in school all your life, eventually you’ll need to get out there and get a job like the rest of us :)