Question: I need to install a couple of installers in the same directory so it conflicts with the Inno Setup uninstaller name `unins000.exe` and `unins000.dat`

Is there a way to change the default name of an Inno Setup uninstaller?

Answer: 
Just dealt with this myself. You shouldn't move the uninstaller executable itself around, for reasons Martin Prikryl pointed out. But I agree it is unsatisfying to have a bunch of numbered uninstallers sitting in a directory with no obvious means of telling which is which.

There is a solution using the facilities Inno Setup provides. In the `[Setup]` section:

```
[Setup]
...
UninstallFilesDir=Uninstall\exe\{#NAME_OF_APP}
...

```

Then in the `[Dirs]` section:

```
[Dirs]
...
Name: Uninstall\exe; Attribs: hidden;
Name: Uninstall\exe\{#NAME_OF_APP}; Attribs: hidden;
...

```

And finally you create named shortcuts in `[Icons]` that point to the uninstallers which will always have the same name because you've sequestered them:

```
[Icons]
...
Name: Uninstall\{#NAME_OF_UNINSTALLER}; Filename: Uninstall\exe\{#NAME_OF_APP}\unins000.exe
...

```

This leaves references in the OS to the uninstallers alone, hides the confusing executable names in a folder the user won't usually see but can still access, and provides named, descriptive shortcuts that can all live in the same folder. You can also give the shortcuts a good icon. For good measure, maybe drop an extra README in the \exe directory to explain what is going on just in case someone gets nosey (they will, naturally).
Inno Setup does not offer any way to let you name (or rename) the uninstaller. Inno Setup takes care of naming conflicts on its own.

Also note that when you try to rename the uninstaller manually (like some answers here do), you break the reference to the uninstaller in *Add or remote application* in Control Panel. 

Even if you fix the reference, there's another problem. When you upgrade later, the new installer won't find logs of the previous installer and won't be able to merge them. Consequently a future uninstallation won't completely remove the application. See the [Appending to Existing Uninstall Logs](https://jrsoftware.org/ishelp/index.php?topic=appendnotes) in Inno Setup documentation.