Three Man Mechanics NCAA

[NM FP Ump]

Went to the local college (DI) this weekend to watch a double header. Saw some mechanics that made me scratch my head. R1 on 3rd, R3 on 1st, one out, both BU on the line but 3 feet from respective base, in anticipation of pickoff attempt(s). I had never seen the BU's this close to the base before, and wondered if this was an NCAA 3 man mechanic, or if it was standard for most rulesets (NFHS, ASA, etc.). I have never called a 3 man before but all the rulesets I have researched don't included this mechanic.