So far as I can tell, there is a day script that spawns certain NPCs during the day and a night script that spawns others at night. If these scripts run day-night-day-night without stopping then by day two, conceivably you could have 4 NPCs (or guars) where you should only have one. That's what I was talking about. Starting a game and adding or removing mods from your load order, might precipitate this problem and cleaning the savegame might fix it.
Simply using mash to install and uninstall doesn't affect load order doubling or any errors left in your savegame. If you haven't added, removed, or changed anything since you started your game, then Mash won't help anyway.
That heppens sometimes in my games where my char is in a cave or inside and loses track of time clearing out the place. He may start around 6 p.m. and before you know it, it's 8 a.m. It's not a game breaking thing, because I can easily accept that some merchants carry more gear than others, therefore needing more pack animals, though I sure wish they had more gold to work with
It's the hit on FPS, more than anything else.
The reason I suggest you may have a problem, is that I have run Starfires NPCs for years and have always had the issue with the guars, until this time, when I didn't mess with my load order after starting a new game.
I haven't had occasion to tinker with my load order for this game as far as mods that use an esm or esm file. I have replaced some pluginless mods the other day due to newer releases. Wrye Mash handles those easily enough, thank goodness
But the pluginless mods shouldn't cause doubling as far as I understand it.