I might could do it.

source: 
LAGS
Entry: 
398
Example: 
I might could do it.
Modal 1: 
might
Modal 2: 
could
Gender: 
Female
Race/Ethnicity: 
White
Age: 
67
Level of Education: 
Unknown
Home Community, Town, or State: 
Unknown
Location Collected: 
GA (Cornelia)
Relation to Addressee: 
subject to fieldworker
Medium: 
Spoken
Sentence Structure: 
1.0
Status: 
Naturalistic