I might could do that.

source: 
LAGS
Entry: 
420
Example: 
I might could do that.
Modal 1: 
might
Modal 2: 
could
Gender: 
Female
Race/Ethnicity: 
Unknown
Age: 
unknown
Level of Education: 
8th grade
Home Community, Town, or State: 
GA (Savannah)
Location Collected: 
GA (Savannah)
Year: 
1972
Relation to Addressee: 
unknown
Medium: 
Spoken
Sentence Structure: 
1.0
Status: 
Naturalistic