I had a problem similar to yours at first, this is what i did:
First, In your server shortcut, make sure it has
so it looks somewhat like this,
Code:
-console -game ts -maxplayers 12 +map ts_awaken +exec server.cfg
Now open amxx.cfg and add this at the bottom:
That is the only place you want to execute the addbot script, if you put it anywhere else it will either crash the server or as you said add twice as many bots.