Can't agree with the previous post. You'll need to quote a rule on PWM limitations.
FIRST supplies us with PWM "Y" splitters in the KOP just for this purpose.
The recommended max for the signal line is probably 2 of the same controller type, i.e., (2) Jaguars or (2) Victors or (2) Talons. Here's a
post on the topic by the Digital Sidecar designer. The Y cables they give us share the signal and ground between two speed controllers, so (2) obviously works.
Jags/Talons/Victors don't use the power from the +5v pin on a PWM output from the Digital Sidecar, so your question might be a bit simpler. Power for those devices comes from the 12v feed they get directly from the Power Distribution Panel.