Will my METV still be valid after being stamped in on a tourist visa in Thailand?

As far as people who get "bad stamped" (stamped in for a time or on an entry stamp OTHER than what they should have gotten) it happens a quite a lot actually

The way the rules are written immigration offices in country are under no obligation to correct a bad stamp and can send you to the passport control at the 'point of entry" (where you stamped in) to get the errant stamp corrected.

I remember a person who stamped in at Chiang Khong (up in Chiang Rai province) but didn't notice he was bad stamped until weeks later when he was down on one of the southern islands :O

He went to the immigration office they said go back to Chiang Khong to correct the stamp.

As he had a valid multi-entry visa he just bounced out/back with Malaysia to get off the bad stamp and re-entered on the correct stamp

CHECK your entry stamp BEFORE you walk away from passport control..

AND

always have a print out of your eVisa PDF that they sent you when you were approved. <- That PDF actually is your visa :)

Remember the stamp they give you IS the stamp you're on (whether you should have been stamped in on a different stamp or not) :O If you overstay because you were bad stamped you are liable for the fines when you exit..

We see these 'self inflicted' problems of bad stamps quite often when people didn't check their stamp before they walked away from the passport control counter :/ Good news is you only do it once, then you catch right on to look at the stamp before you walk away :)

Your last entry on that METV was just a fluke that it stamped you in for the same amount of time as your visa was valid for (you got the 60 day on the METV just like you were supposed to)

The good news is, no the visa isn't cancelled or anything (y) you just didn't get stamped in on it this time (I would guess you got a 60 day free stamp visa exempt entry that has the code ผ.60-ม.17)

Just stamp out like normal when you leave to go to Vietnam

As long as you re-enter the country on or before the 6 month METV eVisa itself expires you'll be stamped in for 60 days.

Just curious; you had the printed out PDF of the METV eVisa right? Handed it along with your passport to the officer when you stamped back in and you still were bad stamped?