http://www.rexegg.com/regex-capture.html#dupe_names

G_Z 19.04.2015 17:33 / 19.04.2015 17:33

In PCRE, Perl and Ruby, the two groups still get numbered from left to right: the leftmost is Group 1, the rightmost is Group 2.

In .NET, there is only one group number—Group 1. This is one of the two exceptions to capture groups' left-to-right numbering, the other being branch reset. If the group matches in several places, all captures get added to the capture collection for Group 1 (or named group token).

Ну, в Perl и Ruby к повторяющимся группам добавляются номера.
.NET, как понимаю, вернёт коллекцию для имени, а не одно совпадение, но Парсеру с таблицей не подойдёт.

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