[CQ-Contest] Dupes vs. Not in Log

[WA7VNI]

Given the discussion in another thread regarding too many
dupes I'd like to ask for the collected wisdom on best
practice when the station you are calling says you are a
dupe but they are not in your own log. This happened twice
to me in the CQWW. In one case I had never heard the station
before so I was a little surprised. In the other (a big EU
station) I know I worked someone just under him earlier in
the morning and suspect that I ended up in his log by being
close enough in freq. for the mistake to occur. I doubt
there was any confusion between my call sign and another in
either case.

What should I do? Do I say "no, not in my log" or just let
it go. Neither of these stations were mult's for me so the
loss on my part was minimal and I just let it pass. Seems
like it would be best for both parties to get it fixed but
what would you as the Op "with too many dupes" prefer me to
do if you say I'm in your log but you are not in mine? 

73 
Patrick 
WA7VNI