I remember hearing stories about that happening pretty often at JAX back in the day. US used to park four to six DHC-8-100/200s outside of a gate at the end of the concourse for the tag routes they'd run (JAX-XXX-CLT) each morning. Because they parked all the aircraft next to each other and boarded simultaneously (all flights would typically leave between 6:00 AM-6:15 AM), it was not unusual to have people doing the plane-to-plane shuffle before rolling out.