This actually confused the crap out of me for a few days because I had to adjustfire on work I was doing when taking it from my DB and inputting it to another server.
I'm sure someone that is more knowledgeable will chim in but you'll see how the spawngroup.id = spawn2.spawngroupID = spawnentry.spawngroupID
and spawn2.id is just another thing.
The spawngroupID is just a auto incrementing field and lots of stuff wont be "in order" but its not important in terms of the npcID so your query
Code:
SELECT max(id) FROM npc_types WHERE id>54000 AND id<54999;
is misleading you.
No idea why the collector is feeding the starting ID's as I've never touched that but wouldnt be that hard for you to column edit with notepad++ into usable values.
Of course I really dont know that much about this, just a little I learned by trial and breaking my db error. Kinda tired so this might not even be on topic.