Yes, you can have more than one MRT on a single page and have both of them insert into tables in your db. Were you able to discover anything by testing out the MRTs' on the page? If you are only getting records inserted into one of the tables there must be something on the page that is preventing the other one from triggering, or makes it look like it it not triggering. If you test one then the other you should have a better idea about how it is currently working.