Ok, not the reference I'm familiar with but I try:
Crown is wrong as pointed out by
@KingCrouchy
If you do an internet picture search (always recommened when you check a watch) for that reference number
1660120
you will find that all other examples are signed "Geneve" on the dial. I didn't find a single one looking like "your" dial.
As the dial looks genuine it could be taken from another watch with a different reference number
Additionally here is an Omega original picture of the 166.0180 which could be the brother watch only without "day"
So I think you should keep on searching for another one!
Good luck!
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