Might should have.

source: 
LAGS
Entry: 
544
Example: 
Might should have.
Modal 1: 
might
Modal 2: 
should
Gender: 
Male
Race/Ethnicity: 
White
Age: 
24
Level of Education: 
Graduate school (Doctoral student at Emory University at time of interview)
Home Community, Town, or State: 
TN (Chattanooga)
Location Collected: 
TN (Chattanooga)
Year: 
1978
Relation to Addressee: 
subject to fieldworker
Medium: 
Spoken
Sentence Structure: 
unknown
Status: 
Naturalistic