Hi Francis,
On a given single page of the main report, the page number information will always be constant. So you can collect the page number and place it in RHa.Now you can collect the same in another varibale using another formula and place it in RHb. So, lets say
whileprintingrecords;
numbervar A:=PageNumber kept in RHa
and
whileprintingrecords;
numbervar B:=PageNumber kept in RHb.
Now, in suppress condition of subreport 2 compare the values of these 2 variables. If they are the same then suppress the subreport else don't.
I didnt get a chance to test this so please check and update if you are able to do this.
-Prathamesh