If you are trying to prevent your own server from being crashed by malicious dupes, consider these official Garry's Mod wiki recommendations: Entity Limits
High-velocity collisions between hundreds of tiny props. gmod server crasher dupe
To understand the standard behavior of the duplication system these exploits manipulate, you can view this tutorial on the Duplicator tool: Garry's Mod - Duplicator Tool Tutorial Nick Dawg Gaming YouTube• Mar 24, 2021 Garry's Mod - Duplicator Tool Tutorial If you are trying to prevent your own
A player can’t manually spawn 5,000 props quickly. But a dupe file can contain 5,000 prop entries. On poorly configured servers, the sbox_maxprops limit is checked after the dupe starts spawning, allowing the overload to begin. allowing the overload to begin.