I just pushed a change for the newest MFR betas (for 1.5.1) that will make BioReactors refuse duplicate inputs. Anything that behaves nicely with the new vanilla ISidedInventory (I tried MFR and vanilla hoppers) will respect this, so you can just jam whatever in there and not need to worry about it being filled with 8 stacks of oak saplings. Now you're just down to figuring out how to send it 9 kinds of things at once.
