I've noticed that when I get messages regarding pets that fits my triggers I often get multiple notices. Often just 2 but I just recieved 5 messages for the same auction regarding a dragon that fits my trigger.

This means that you have several triggers that match the same pet. For example, you can set 3 triggers: one for male dragon, seocnd for green striped dragon and third for firebreathing dragon. When someones creates an auction for a green striped firebreathing male dragon, all three triggers will be triggered.