My brother and I often travel together and we both have biometric passports. We are not twins but we do look alike, I wear glasses whereas my brother doesnt. However, whenever we arrive at a destination and attempt to use the e-gates at immigration, the first one of us to go through the gate is successful, whilst the other one will be rejected and is therefore directed to a manned gate to be let through. This has happened every time since the introduction of e-gates. We've tried going through the gates at the same time in two gates in parallel and we've tried going through the same gate one after the other (also in different orders) and the same thing happens.
This doesn't just happen at one airport; it has happened at different airports across different countries (specifically, LHR, LGW, LTN, SXF and AKL as far as I can remember off the top of my head). This problem does not seem to occur if we're not travelling together (for instance, I've navigated the gates successfully when I've travelled with work, whilst my brother had no problems when he went on a solo trip a few years back).
Though this isn't a major issue, I'm just curious to know what might be causing this and if there's anything we can do about it?