Hello everyone. I look forward to learning more about Windows 10 and my computer. I was looking at the event log under security and I noticed I have multiple Account Names and Logon Id - see below

Security ID: SYSTEM
Account Name: HENDERSON$
Account Domain: WORKGROUP
Logon ID: 0x3E7


Security ID: HENDERSON\Rob
Account Name: Rob
Account Domain: HENDERSON
Logon ID: 0x66EA9E

Does this mean someone else is also logged onto my computer somehow?