It is possible the taller pole supported wires for electric lighting service while the shorter one had telephone circuits upon it. Neat "old school" pole line architecture is seen here. Note the wooden blocks separating the buckarms (these had a bolt through them as well). I recall the latter upon some local electric distribution lines around here through the 1980s. There also could be some of these "blocks" still in service within former Boston Edison territory where a fair number of old poles from the teens and later still stand.