How is the system different after the first and after the second call?
If there is an rm executable in the current directory, and also one later in your PATH, the second run might use a different rm that could do whatever it wants to
This is actually a likely scenario, as it is common to alias rm to rm -i. Though your bash config will still run after .bashrc is nuked, some might wrap with a script instead of aliasing (e.g., to send items to Trash).