'Trym' has produced a lot of seedlings but not many of them have outer petals that so closely resemble the inner petals as those of 'Trym' itself. 'Trympostor' was so-named because it resembles 'Trym' quite closely, although it flowers earlier and is more vigorous. 'Trypostor' is often misspelled as "Trymposter" (with an "e" instead of an "o") but that is a name I coined on this forum over a decade ago for a seedling raised by johnw.