Speaking captain?

[Freddy]

Originally Posted by rawhi1

I can't find it anywhere in the officials manual, but is it mandatory to pick one speaking captain of a team that has two or more captains in the meeting with the referee.

Ain't no such thing as a "Speaking Captain", though it is a chronically habitual thing many say. Kinda like, "Tonight we're playing the black line all the way around," "Play defense with your feet", etc. Ugh.
3-1-1 says, "Each team consists of five players, one of whom is the captain."
Ergo, each team shall have no more than one captain. Only one captain shall each team designate. Captains, of which each team has one, will be singular in nature respective to each team, such number never constituting more than two total for both teams. Divide the number two by the number of teams involved and then shall the product be the number of captains each team shall have, which is one. Sorry....
Ceremonially, any number of players may attend the pregame meeting. Heck, make it a big, warm-and-fuzzy-feeling Kum Ba Ya moment and have all the players attend, that's ok. But it's up to you to ask, "Which of you is the captain?"
I'll leave it to you to identify the designated privileges and duties ascribed to the two captains. That's found elsewhere in the rules book.