bridging will decrease the load impedance twice and may become a heavy load for amp unless it has unlimited current to support that. Notably if your speakers going somewhere all the way down to 2 ohms, the load impedance per amp will be nearly 1 Ohm and unlikely there's an amp stable to load nearing short circuit.
technically I would only use vertical biamping for that particular matter.
biamping with same amps works the best as you simply doubling the power. The distribution of power is controlled by your speaker internal crossover pretty much.