Hi!
According to the
entry requirements for the Bachelor of Science/Arts double degree, there is mid-year entry available (provided you meet all the requirements). In terms of whether you will be able to transfer credit from a previous course, it's hard to say for sure (since credit is assessed on a case-by-case basis). In general, if there's a significant overlap between the units you've done (e.g. at RMIT) and units at Monash, then it's likely you'll be able to receive credit. You might find
this link useful, which lists the outcomes of all previous credit transfers. Since the Arts course has some free Arts electives, you might also be able to obtain unspecified credit (where there is no equivalent at Monash but you are still given credit points for previous units completed at a different uni) towards these (but it's best to ask Monash directly for this). You should also have a look at the units you'll be completing at Monash in the
Science/Arts double degree, and see whether you can complete equivalent units at RMIT.
Hope that helps!