I recently intall a second bathroom and put in a toilet that clogs often while my first toilet has never been a problem. The first toilet has an air pressure tank and the second does not. It is a more basic/traditional model. Can the location or quality of the toilet be a factor or is a toilet a toilet when it comes to flushing?
Location can be part of the problem at times. Are both toilets connected to separate branches on different floors and to the same stack and/or is the new toilet wet vented? If so, I believe that a blockage in the venting system may be the problem, or possibly something wrong with the flushing mechanism, maybe the flapper isn't staying open long enough. Of course, it could also just be an old fashioned clog as well.