Multiple trapeze is an act entailing the use of more than one trapeze

Trapeze

A trapeze is a short horizontal bar hung by ropes or metal straps from a support. It is an aerial apparatus commonly found in circus performances...

, typically two or three. In these acts, multiple people perform simultaneously.
The most common type of multiple trapeze is a "triple trapeze". A triple trapeze has one long bar, held up by a ropes, basically three trapeze's put together, with the middle trapeze sharing the ropes of the other two. Multiple trapeze can also refer to an abstract structure with trapeze like structures, inside which multiple artists may perform.

An experimental cage-like structure was created by Cirque du Soleil

Cirque du Soleil

Cirque du Soleil , is a Canadian entertainment company, self-described as a "dramatic mix of circus arts and street entertainment." Based in Montreal, Quebec, Canada, and located in the inner-city area of Saint-Michel, it was founded in Baie-Saint-Paul in 1984 by two former street performers, Guy...

 for their show Varekai

Varekai

Varekai is a Cirque du Soleil touring production that premiered in Montréal in April 2002. Its title means "wherever" in the Romani language, and the show is an "acrobatic tribute to the nomadic soul"....

which was ultimately scrapped in production. However, the structure did appear in the 'Making of' documentary, 'Fire Within.'