Hi Marc,
The one clue that might prove that it could be an actual Merckx frame is if you can get a good look at the rear brake bridge. The bridge should have the Merckx name scripted into the bridge. The brake bridge is usually a unique shape and I thought in the one view that I could see that shape. You can see an example of the brake bridge on a Merckx currently for sale on ebay here :
Hope that helps.
Philip Huyghe
Rochester, Mi USA
The seller is listing this as a "refinished" Merckx . In an email to me he states that the bike was repainted , re-decaled , and has no visible serial # . Are there any sure-fires signs that this is an actual Corsa Extra ? Listing # 290293207548
Marc Frazer
Baltimore , Md