Why is the same patch being repeatedly applied to the same application? I thought a vulnerable module would only be patched once.

This is normal behavior for in-memory patching: 0patch doesn't modify executable files on your file system, but rather applies patches in-memory when any process loads a module we have a patch for (so-called patchable module). This means that the same patch may get applied to an application every time that application gets launched, and in case of web browsers that launch a separate process for every browser tab, this leads to each of these processes being patched separately, sometimes in a rapid succession.