How to refer to a group without ambiguity in a regex?

Suppose I want to realize a replacement in a string: "aabbcc11dd ee" -> "aabbcc112dd ee", I can use a regex like this within StringReplace:

RegularExpression["[a-z](\d+)[a-z]"] -> "$  12" 

well, if only the right-hand side "$ 12" was interpreted as “the group 1 with the digit 2” instead of “the group 12”.

So, in Wolfram’s regex, is there any syntax setup to eliminate this ambiguity? I know that, for example, in Python there is something like '\g<i>', which, because of the angled brackets, allows no room for ambiguity.