Why does eBay allow multiple Sellers to sell the same object under 3 diff #s?

[onebadwolf]

This exact same watch is listed by 3 different sellers, under 3 different eBay item numbers.

antique-yokohama-jp                 #143898245847

https://www.ebay.ca/itm/Casio-Marlin-W-550-Digital-Vintage-Mens-wl19619/143898245847

tomimu64                                      #154226305714

https://www.ebay.ca/itm/CASIO-W-550-81-Watch-with-swordfish-top-Vintage-working-product-Digital-rare...

Oriental-Vintage-Modern           # 124412420109

https://www.ebay.ca/itm/VERY-GOOD-Rare-Casio-W-550-Mens-Watch-From-Japan-EXPEDITED-SHIPPING/12441242...

What if 3 people buy the same item?

[pjcdn2005]

I would guess that when one listing sold the seller would take down the other 2 listings. 

Duplicate listings aren't allowed although I doubt that ebay actively looks for them.  You can report the listings but ebay doesn't always remove them.

[marnotom!]

At least two of them will get ripped off if they're not careful.

[femmefan1946]

I'd question whether two of those sellers had stolen the real seller's listing.

EBay has an option of copying another seller's listing and pictures, which is meant for mass market items not unique collectibles. But it can be misused.

[pjcdn2005]

All 3 sellers are listed as being in Japan so it's unlikely that they are 3 different sellers.

[marnotom!]

Locations can be faked, though.

[onebadwolf]

Except that the 550 is one of the rarest Casio's. eBay goes years between even having one listed, much less 3.