Some nationalities can be issued with more than one valid passport for the same nationality for various reasons. Does anyone know if switching these to enter Thailand might be frowned upon or tracked somehow through the Thai immigration intranet?

This depends on what kind of visa you have for Thailand.

You got a non-imm B, O, OA or whatever in one pp? Not even think to use the other one on your next entry. I did see my own records on the screen for a couple of times. They know who you are.

I use one for LoS only. Fine, the other one travelling around by courier.

But I never would use the non-LoS to come here

What is the extent of the info they keep, and the method they have for sorting through their databases. If they search by name and date of birth then they will find out a person is using a second passport, and this will make them suspicious.

But if they just search by passport number, everything will be OK. I suspect the former though, because they would have to be very stupid to do the latter.

just as long as you enter and leave Thailand on the same passport, you will be fine. Doesn't matter if it is a second passport of the same nationality, or a second passport by virtue of dual nationality.

Thai Immigration computers are capable of searching by name and date of birth. I wonder why you'd want to use different passports entering Thailand on different occasions.

When i was working in Malaysia, I travelled to Thailand on numerous occasions on business (two/three day visits). I was at that time a holder of two British passports and I used whichever came to hand first. I had no problems whatsoever.

I wonder why you'd want to use different passports entering Thailand on different occasions.

A number of reasons I might assume. Here?s some I just thought up not related to the original question which was more directed at the legality of using multiple pps in Thailand.

1. Employer may need different passports depending on country of employment?

2. Limiting the amount of time apparently spent in one country by spreading visa stamps between passports for tax or other reasons?

3. Cheating on the wife?

The list goes on?