The ender chests on multiplayer

No, the Ender Chest's contents are tied to individual users like an inventory extention they can only access while interacting with these chests. It doesn't matter who built/placed the chest, everyone only ever sees their own Ender Chest inventory.

The player who built a specific Ender Chest and whether or not you've built one in the past are irrelevant to what you see in the chest. It doesn't matter which Ender Chest you look at, each player will always see the same things in their Ender Chest, and it's impossible to see what anyone else has stored in their Ender Chest, much less take from them (without mods).