Ubuntu 12.04: top batch mode - very strange behaviour

[Sergey Arlashin]

Hi!
I'm using Ubuntu 12.04 64 bit.
CPU: Intel(R) Core(TM) i7 CPU 930
procps version 3.2.8.

Not long ago I decided to monitor CPU consumption of my virtual machines (KVM based) with top. In order to do that I set up my monitoring system to run the following command every once in a while :

top -b -d 1 -n 2 -c

and then get the information about certain KVM guests from the last (second) iteration.

Everything worked well except for the fact, that every so often I get just enormous values of %CPU for some of my KVM guests.

Sometimes it shows 1000%, 2000% and even up to 10000%. I have only 8 cores (4x2) available and the maximum %CPU value can be 800% I suppose. So in my understanding anything above 800% is not normal.
Moreover I don't see anything like this in interactive mode while running:

top -c -d 1

So the question is - is it a bug? Or may be this behaviour of top in batch mode is considered to be normal? 

Thanks in advance. 

--
Best regards,
Sergey Arlashin