Help With Ric

While I'm not familiar with the paper version of RIC, I'm guessing that the two numbers are here referring to a legend break or bust design. A coin shouldnt be applicable to 2 RIC numbers, as far as I know.

While RIC is an excellent reference it is full of errors and can be very confusing IMO. I can understand where the differences in the mint mark would be a separate number, but when the coins are identical including the mint mark than there should be no difference in the RIC number. This I can only chalk up to being one of RIC's many mistakes.

There's not an error here, it's just a confusing set of charts to read, but it makes sense eventually.
RIC Vol 9, p. 114-115 (what you have shown above) give the mintmarks associated with each group.
There is overlap between obverse legend types so you first have to classify the coin by the mintmark on pages 114-115.
The further by bust type to get the correct attribution.

It's easier if you substitute "group" for "period" in the headings - makes more sense that way to understand the charts. Your confusion probably stems from them saying that there was overlap between the different periods, but in actuality they're classifying them by groups. So using 'groups' instead of 'period' makes more intuitive sense when trying to understand this section from pages 114-136.

So your R QVARTA is correctly attributed to RIC 24a, since it has a mintmark from the 2nd group, you can confirm by checking the bust type. Rome 24 lists bust types 1(A), 2(A), and 3(A) where 17 only lists 1(A) and 2(A). So if it's 3(A) it's definitely 24, although the mintmark should suffice.

Same goes for the other one, but it should be 24b not 17b since the mintmark R PRIMA is included in the second group, also assuming you have bust type 2(A).