The reason this occurs is that in order to have a portable and sane
implementation time.strptime() uses the re module to parse dates. The
issue here is that by specifying the same format twice the re module is
complaining that there are two named groups with the same name, leading
to a conflict.

About the only solution I can think of that doesn't require some massive
rewrite is to drop named group usage from time.strptime() and move to
positional groups by keeping track of the order of the formats and
zipping the format order and results together or something.

But I don't plan on doing that personally as that would require writing
a parser for format strings as well. But if someone manages to get it to
work I would be willing to review the patch.

Setting the priority to low as this is easy to work around since you
just use one set of date information instead of two which is redundant.