We have 2 amplifier from one manufacturers.
Amp 1 - 4 channels, 125 Watt, Maximum Current: 60 Amperes peak per channel.
Amp 2 - 2 channels, 125 Watt, Maximum Current: 100 Amperes peak per channel.
If we connect these amplifiers to identical speakers, first amp using bi-amping (all 4 channel in use)
and another (2 channels) just using bi-wiring cable.
Which amplifier will have more control on speakers?
Hard to say. 125W of average power is 250W peak. That implies only 11.2A peak at 2 ohm load. You will never need 60A for anything. You might assume that 100A amp has beefier power supply, but it might not be true. 60A amp can have better and well regulated power supply, but has current limit of 60A by design. Within this limit 60A amp might actually have lower output impedance than 100A amp.
Difference of output impedance between, for instance, 0.05ohm (DF=160) vs 0.1ohm (DF=80) means nothing for control of the speaker (damping) since you already have speaker’s resistance in series, that is in order of many ohms. The best DF that you can get in reality is about DF=1.5 since impedance of the speaker at bass frequencies is about 2/3 of nominal (1kHz) speaker’s impedance. You don’t want to make it worse but 10x better DF=15 for amp should be satisfactory. Big numbers like 60A or 100A is pure specsmanship. Would you buy computer keyboard because it allows to type milion words per minute?