Because Torpedo signals are data streams, they cannot be mixed without corrupting the data in the stream.
The TM-105 is a message buffer with 5 separate inputs and a single Torpedo output. As messages array at the input ports, they are buffered until the output port is free to send them on. Up to 5 messages may be buffered at once, if the buffer fills, messages will be dropped. A set of leds indicate how full the buffer is at any one time.