It wasn't common practice in pre tourist days. During the roads history, locally sourced narrow gauge sized untreated ties were used. That said, there are several possibilities. One, its possible that in recent years, standard gauge ties were cheaper and more readily available than narrow gauge sized (7 feet?). Another thought , in the last years of operation they may have had standard gauge ties stockpiled in Mt Union, and figured use what they had rather than order narrow gauge ones.
Probably mentioned before, the PRR had a tie treatment plant in Mt Union, complete with a 2 foot gauge in plant railroad. The EBT never used this source, instead buying the untreated ties.
brian b