If you're referring to this feature

"By default the CGI module implements a state-preserving behavior called "sticky" fields. The way this works is that if you are regenerating a form, the methods that generate the form field values will interrogate param() to see if similarly-named parameters are present in the query string. If they find a like-named parameter, they will use it to set their default values."

I don't think this has anything to do with what the OP is observing. There's no "regenerating a form" in the above code. Actually, there's no form involved at all, as the OP is directly supplying the parameter in the URLs called via SSI. A directly specified value ?count=10 should clearly override any value from a previous request.

I don't think this has anything to do with what the OP is observing.

Ok.

But, there is no way the OP could observe anything like he claims :) "ModPerl::Registry" does not support SSI

"ModPerl::Registry" does not support SSI

??   It's mod_include that handles SSI and - when #include virtual is being used - it makes a sub-request which is then handled by ModPerl::Registry the usual way as if it came from an external client.  See Re: Apache Registry with Server Side Includes.