<?php
var_dump(preg_replace('/@@SOMEPHENTITY@@/', 'XXSOMEPHENTITY@@', 'This sentence includes both @@SOMEPHENTITY@@ and XXSOMEPHENTITY@@ but only the replacement will show up in double'));
string(113) "This sentence includes both XXSOMEPHENTITY@@ and XXSOMEPHENTITY@@ but only the replacement will show up in double"
Output for 8.3.5
Warning: PHP Startup: Unable to load dynamic library 'sodium.so' (tried: /usr/lib/php/8.3.5/modules/sodium.so (libsodium.so.23: cannot open shared object file: No such file or directory), /usr/lib/php/8.3.5/modules/sodium.so.so (/usr/lib/php/8.3.5/modules/sodium.so.so: cannot open shared object file: No such file or directory)) in Unknown on line 0
string(113) "This sentence includes both XXSOMEPHENTITY@@ and XXSOMEPHENTITY@@ but only the replacement will show up in double"