Cant block own email address

[Barkas]

Hi All. Can you advise me on the following in case its a security issue for me. I have been using the same hotmail address for 20 years, tonight I have had a junk/scam email from someone, but what worries me is that the sender has used my exact same hotmail email address to send it. I did not know 2 people could have the same email address.....I usually block such emails but outlook wont let me block this email because it says it " Its Your own email address and cannot be blocked".
Will emails sent to me be also be sent to the fake address, and Is it a security issue or should I ignore it. Thanks for any advice.