From the docs:
Wildcards include * which matches any 0 or more characters, and ?, which matches exactly one character. Unlike Unix shells, the / directory separator is not special, and can be matched by either * or ?. The resources are always expanded into their absolute form before expanding.https://www.modpagespeed.com/doc/restricting_urls
That's not exactly clear; I'm assuming that ? is like in a regex and matches 0 OR 1? Because if it matched exactly 1 then it would be irrelevant.
If I'm right that ? matches 0 or 1 then I wasn't sure if there was a specific reason to use two lines instead of a wildcard (speed to process, maybe?), or if it's just something from the olden days that hadn't been updated. I use * throughout my configuration, too, but in most cases I really just want it to match 0 or 1. The ? wildcard is marginally faster in regex, so it would be a better choice if it works the same here.