It wouldn't matter which image he chooses, the mage rolls the d20 to see if you hit the mage or the image. If you see the images at anytime, then you never know which is the true image. Think of it like Naruto using the mass shadow clone jitsu, no one ever knows who the real one is, they attack and the clone disappears. This is that spell.The ruling seems pretty clear to me. The only potential problem is the way 5e deals with attacking invisible targets (which is effectively what the person would be with your eyes closed). The default rules have the player "guess" where they are attacking, and the GM has them roll (even if the target isn't there). That particular rule is one that is mechanically useless, and requires the usage of a combat grid, or some on-the-fly ruling.
If the GM is OK with the player being able to "guess" the right location of the real enemy with his eyes closed (sort of how actual blindfighting tends to work -- you aren't swinging wildly to your right when the guy is moving around to your left), then closing his eyes means he just gets the disadvantage to hit and otherwise ignores the images.
But if your GM does something like setup 4 extra identical pieces on the board, so that the player has to choose which square to attack in, then closing his eyes would make things worse by not only getting disadvantage, but also because he's still having to randomly figure out which square the mage is in.
Anyway, it's the kind of thing should probably be cleared up beforehand.
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