Louisiana had basically two types of militia, the Regular Militia and the Volunteer Militia. There was a unique difference between the two. The Regular Militia was organized on geographic boundaries (ie. Parishes) and every man between certain age range in those boundries were required to enroll in the Regular Militia -- unless they belonged to a Volunteer Militia unit. The Volunteer Militia units were different than the the Regular Militia in several ways: memberships was (as it says) voluntary, they elected their officers, they could have a standard uniforms, they had to arm themselves unless in active service of the State, and they ould volunteer to be transfered to service in the Provisional Confederate States Army. In the case of the two units you mentioned in the 8th Regiment of Louisiana Volunteers, they both seem to have been formed as volunteer militia formations, and both were mustered into active State of Louisiana Service for a few days prior to being mustered into Confederate Service as part of the 8th Regiment.