You'll find that in Stock and other mods also. It's the nature of the beast. One thing you (hopefully) wont' find in FotRSU is roving bands of IJN DD in various places in the game, milling about looking for a fight - with your computer resources! If you get into mid- to late-1943 in some iterations of the game, you'll find that, and they're from the Jap_HarborTraffic.mis file also...
Like I said though, the forthcoming v0.64 should "fix" the multiple spawns in harbors. We'll see...
