multiple scanners, problem?

[Funk Gabor]

I was playing around with MailScanner using two scanners.
I've set it up to use inoculan 4 and f-prot - in this order.
It was successfully catching eicar using each one separately
and using the two together as well.
Today - in this klez heaven - I received a klez.H, and it wen't
throu' with "Found to be clean". I took apart the message and
found out, that I have an older f-prot database which doesn't
recognize klez.H, but inocucmd recognized it. I then disabled
f-prot, leaving inoculan as the only scanner, 10 minutes later
another klez.H was found by MailScanner then. I wonder if
the results of the different scanners are not properly OR-ed,
or I simply screwed up something somewhere.
Anyone has similar (or any) experience with multiple scanners?

G.