I have just checked some old tickets of ours from nov '07 also 2 day passes
and it's quite strange as 3 of the tickets have been punched twice and 2 of the tickets punched once only, but all 5 of us entered and left the park together on both days. Our tickets from March last year though have both been punched twice - 2 days, and 2006 5 times - 5 days so I think you're probably alright, if I'm understanding correctly what you've bought i.e. a 2 day ticket with 1 day unused, therefore one punch mark for the one day used - the only way you can be certain is to try them at the turnstiles.
To be honest it's one of the reasons why I wouldn't buy part used tickets off Ebay. I've even seen hopper tickets advertised on Ebay as having 3 days DLRP entry and 3 days WDS entry, only part-used because the seller had only been into WDS for 1 of the eligible days and stayed in the main park for the other 2 - giving the impression that those tickets still had a day for the main park and 2 days for WDS remaining on them, when in fact they had nothing left.
Hope that they're OK, does the seller seem genuine, good feedback etc., I'm sure they won't mind you just clarifying what/how exactly they used the tickets.
Just seen your new post - I have never seen or heard of a ticket with more than one validity period on it, and you won't be able to use these in the summer season, to me that reads that they are valid for any one day only between the low season dates given and the hole indicates that that day has already been used, definately worth clarifying with the seller where they got them and why they're like this. Sorry but I don't think it looks good - hope I'm wrong.