Origin of Germanic *ebnaz "even"

The Germanic *ebnaz word, "even" in English, "eben" in German, "jafn/jamn" in Old Norse, "jämn" in Swedish, "even" and "effen" in Dutch, etc., and "ibns" in Gothic -- is its origin akin to Latin <imitor> "to imitate, copy, ape" and <aemulor> "to emulate, rival", hence originally *imnaz, not *ibnaz or *ebnaz, and with the "equal" meaning being the earlier meaning, "level" having developed secondarily (like Sanskrit <sa:ma->)? I read somewhere a long time ago that some scholars think this may be the case. If on the other hand the "level" meaning is earlier, what then would be its origin? My Webster's New World College Dictionary Fourth Edition says that "even" possibly goes back to PIE *yem- "hold together", which it lists as the root of Middle Irish <emon> "twins" (and presumably also Sanskrit <yama-> "twin" -- I'm saying this from memory, maybe it's <ya:ma-> or something else). Does this make sense to anybody? I fail to see any semantic connection
between "hold together" and "twins" or "hold together" and "equal/level", though a connection between "twins" and "equal" is very plausible.

Andrew