If you destroy the end gateway, and use /setblock to create another one, you will stay in the End Islands and it will create another gateway right above the old one. Sometimes it will move it to the side or when you destroy it and place blocks, form a random one without using the gateway.
MC-115624
Multiple Gateways!
Resolved
Invalid
0
You're not supposed to be able to destroy the gateways, as the portal and bedrock are both unbreakable.