I think what probably happened with Shrek is that it got a lot of press as being a satire with mature themes which suggested to a lot of people that it was more of a movie for adults. While Toy Story lacked profanity and references to oral ***, I thought it was a movie that had plenty of comedy that adults could enjoy on their own although it may not have been perceived that way by the general public. That's probably where the extra box office sales come in. That and inflation. When I went to see toy story I was paying $4.50-$5.00 for a ticket and now I'm paying around $7.50. Older box office records are getting much easier to beat these days if for no other reason than inflation. I have a feeling that a sequel, though probably successful, will not do as well as this first one. I for one went because of all the hype it was getting and was underwhelmed (perhaps my expectations were high because of all the hype) and would be in no hurry to see a part two. I'm guessing that I'm not alone with this.
I thankfully, have yet to see a shrek doll or bean bag character yet though!