Perhaps they were Venturers who can be both an adult when registered with a troop (and over 18) and a youth when registered with a Crew (and under 21). Yep it is true -- a venturer youth can be an adult and registered as both at the same time when the scouting registration is with a troop, and the second registration is with a Crew. Confusing isn't it. When acting as a Venturer, it is appropriate for the venturer to wear the youth rank on his uniform. If he was wearing a scouting shirt, one would need to see if the strip over the right pocket said venture patrol, or venture, as some Crews have adopted that uniform.
50 year+ scouter -- have held almost all adult leader positions in Cubs, Scouts, & Venturing, currently serving as Council Scouting for Youth with Disabilities Chair.