We have had customer inputs of 2 different types of format for VM_UUID being reported on EC2 instances. 

This seems to be related to the decision taken by Amazon, where AWS was transitioning instance IDs and reservation IDs to a longer format.

Link: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/resource-ids.html

Prior to January 2016, the IDs assigned to newly created resources of certain resource types used 8 characters after the hyphen (for example, i-1a2b3c4d). From January 2016 to June 2018, we changed the IDs of these resource types to use 17 characters after the hyphen (for example, i-1234567890abcdef0).

Only newly created resources receive longer IDs; existing resources are unaffected.