My Matthew. Welcome to life sci
Im not sure if your conflicting mandatory classes (like 2 labs you have to be at no matter what) or if its just 2 lectures etc...
In my last year before I graduated I conflicted english and physics which was fine bc english lec was useless and physics was online, and i managed quite well. Other than that situation I think it would be a poor decision to have conflicting courses, unless of course you have an established buddy study system, in which case go right ahead.
Source: I'm a graduate student, ive gone through the whole mess of undergrad. If your interested in grad/med school for the future and you have questions, visit my blog www.insideminds.tk and leave me a comment or pm me on this forum. I usually answer within a day or so. good luck