Futuristic / Monorail style trains ??

Plarnold, out of interest when was Advance launched? I'm really new to the scene so have no history with them. Although I have noticed that some of the loco sets have been re-issued with the same code, but with a totally different loco. I assume this is perhaps to address issues with the original releases that you alude to. But the big question to a newbie to the range is which one is which? I mean if you have two totally different locomotives with the designation AS-05 for example is there any way to determine which is the original (potentially flawed) design and which is the latest new release?