unfortunately the collection thumbs are tied to all the thumbs. So if you say display 5 per page it does it across all pages that display thumbs. What you could do is just copy this function and name it something unquie and apply that unquie function to the collections page only. You would also have to make a copy and paste of this feature in the admin php too so that you could change it from the UI. Probably a little more then you bragined for but its just finding, then copying, then pasting + rename ; P
Otherwise no sorry.
So if you want to use the default setting to change the amount of displayed thumbs on all pages go to plog-admin and set the thumb number to the number you want.