This is specific to mtg, though it might also be an issue if other plugins have a "Format:" option to search for cards as well.
The issue is when searching for reprinted cards; cards that appear in more than one set. Basic lands, for instance. If I want to find basic land cards, I can just search for Basic land, and all of them will come up. Then, I can restrict it to standard, and I'll get just the land cards from sets currently in standard. Then, if I only wanted to see one of each, I click "ignoring doubles"... and they all disappear, whereas, I was expecting to get one of each land. It filters out all of the lands, rather than leaving one of each.
The problem, I assume, is the filtering precedence. What I assume is happening is the program is starting with all the basic lands, then applying the "ignoring doubles" rule to narrow it down to one of each, before applying the "Format: Standard" rule, and since it chose a non-standard set when it ignored doubles, that card is filtered out. Ignoring doubles should be the last rule applied.
(And this is an issue for more than basic lands. Any reprinted cards in standard, such as Cancel, are effected)
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