The Sacramento Northern made extensive use of locos with one pan and one pole (and third-rail shoes, too!) to utilize the SN's weird admixture of power supplies--pans were used on interurban catenary track and on freight lines, poles were typically used in town on passenger lines, third rail used north of Sacramento outside of towns, and all units crossing Suisun Bay on the ferry RAMON used poles to board the ferry (it wasn't set up for pans.)
SN 1005 with pan up and pole clearly visible
Box motor 601 with pantograph and two poles
GE steeplecab 650 with pan & pole