Originally Posted by
nongfu
Thanks Mwenenzi! I entered Ireland on my main USA quadruple thick passport (I double checked and found the big entrance stamp) and Im now in Scotland. Ill do some of Scandinavia before returning to USA for a few days. I want to have a Russia visa waiting for me, thanks to you I believe Im good to go! Ill mail my secondary passport to TRAVISA next week.
Thanks again!
Your main issue will be the UK exit "controls" (or lack thereof). You'll want to make sure you check-in to your flight leaving the UK/Ireland using the same passport you used to enter UK/Ireland (I believe it should have an entry stamp - I'm not sure about border controls between Ireland and UK though, but I don't think they track this). Otherwise you might not be registered as having left the CTA, and you could get investigated for an overstay the next time you enter the UK or Ireland. (I'm not sure how integrated the UK and Irish systems are, but presumably they can cross-reference entries and exits for both.)
(This is similar to the US: as a foreigner I need to give the airline the same passport that I entered on, so that the CBP actually know I've left - but CBP won't actually check it themselves.)
In other words, no need to care about the US since you're a citizen, but you do need to care about the countries you're visiting if you want to avoid issues the next time you visit. If you're 100% sure you'll never visit the UK or Ireland again (as an emigrated Brit, I fully understand), feel free to ignore this.