As to Dom's comment, you can run two TC50 or a TC50 and TC100 using only one footswitch.
The amp with the TC footswitch must have the rotary channel selector set to 0. The other amp should be set to any other channel position and should not be at 0. Connect a midi cable from the amp with the footswitch connected, midi cable plugs into midi thru/out jack, then plug the midi cable into the midi in jack on the TC that does not have the footswitch.
Set all of the toggle switches on the front and back panels to the same setting. If you do not do this, whacky things will occur.
Always power on the amp with the footswitch connected to it first. It can stay in standby mode. After that, power up the amp that does not have the footswitch connected to it.
The inputs of the amps, should have some sort of signal splitter with one isolated output to prevent ground loop coupling between the amps. It is also advisable to have a signal splitter that has a ground lift and phase shift control. Lehel P-split II or III have such. They do not require any power as the unit is just a signal splitter. An ABY switch device will work too. I use the Mesa Switch track but not required. Earth Quaker devices has the Swiss things, Radial engineering has their own unit. Guitar signal plugs into the ABY switch or the chain of devices you place on the front end should be in front of the ABY switch. (Note: some overdirve, boost, or distortion pedals may not play well with the units with input buffers, Mesa switch track and Radial engineering as examples. The Earth Quaker devices has two FX loops for use with overdrive and distortion effects that are not suitable on the input buffer, and the other loop is for devices that are compatible with the buffer).
Do not expect a mono to stereo out pedal to work as a reliable signal splitter. It may get noisy if there is a grounding issue between the amps. Since the TC amps are the same, it may be fine. I found the contrary that I needed to use one amp with an isolated channel like the Lehel P-split or ABY box that has that feature.
As for the FX jacks, no point in connecting them from amp to amp, sure you can cross link them but that only slaves one amp to the other.
Stereo effects units that have left and right channels (inputs and outputs) can be used. I run just one Strymon BigSky effect which has a left and right channel. the FX loop on the amp on the left goes to the left in/out connections and the right on the right in/out connections. Just note that some FX pedals may need to have a jumper or switch set to operate in stereo mode if so equipped.
Mesa amps that have the midi control can be coupled together with the daisy chain method if they are the same series of amp. more than one TC series amp can be used with one footswitch. Do not mix and match amps. In other words, a TC cannot be daisy chaned to a JP2C as the footswitch commands are different between the two amps. One cannot use a Mark VII and JP2C with the same footswitch either, different commands, and instructions will do different things. If you have a third party midi controller, by all means you can use any number of Mesa amps with the midi interface, you just cannot use the Mesa footswitch with the amp when using an external controller or it may damage something as stated in the manual.