Might could comes from Mississippi/Alabama. Eudora welty had her 2nd grade teacher yell at her back in the 1920s about it in Jackson and it slowly became Texan parlance as people moved west from Mississippi.
“Might could” is actually a grammatically-nuanced expression that supplies what is lacking in English among those who don’t say it, or don’t know the subtle but real distinction between “could” and “might could”.
Other languages provide for this distinction.