I might could do it.

source: 
LAGS
Entry: 
410
Example: 
I might could do it.
Modal 1: 
might
Modal 2: 
could
Gender: 
Male
Race/Ethnicity: 
White
Age: 
76
Level of Education: 
10th grade
Home Community, Town, or State: 
LA (Mount Union)
Location Collected: 
LA (Mount Union)
Year: 
1975
Relation to Addressee: 
subject to fieldworker
Medium: 
Spoken
Sentence Structure: 
1.0
Status: 
Naturalistic