Why are Windows NT user profiles created with extensions of .000, .001, and so on?
The following is from the MSDN article Q185588,
"Guide To Windows NT 4.0 Profiles and Policies (Part 3 of 6)":
"Should multiple users with the same account name
log on to the network, separate distinct profiles are created for each. For example, if
multiple users with the account name John Smith log on to the computer, the first John
Smith is assigned a folder named JohnSmith. Subsequent users with the same name are
assigned folders named JohnSmith with a numerical suffix appended, for example
JohnSmith.000, JohnSmith.001, and so forth."