Please assume the following:
I am travelling from Bangalore to Singapore transiting through Bangkok. I am an Indian national. I will be travelling on one ticket. I won't be leaving the airport. I do not have check-in baggage.
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If you're travelling on one ticket then your checked baggages will be forwarded directly by the airlines. Thus you'll be transiting airside and won't have to clear immigration or customs. So there'll be no immigration stamps on your passport unless you plan to leave the airport and go visit Bangkok.
Source: Have transited through Bangkok several times