Wix custom action executed twice during upgrade?

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msi

installer

InstallShield

I have a custom action which during upgrade,removes certain files before installFiles which puts the new files back.What I am noticing is the action is called 2 times.
1.Gets called and deletes the file.
2. InstallFiles copies the new files back.
3.Again gets called and deletes the file.(Should not happen).

My custom action looks like -

<InstallExecuteSequence>
			<RemoveExistingProducts After="InstallFinalize" />
			<Custom Action="NEWER_VERSION_PRESENT" After="FindRelatedProducts">
         NEWER_VERSIONS
			</Custom>
			<Custom Action="DeleteourFiles" Before="InstallFiles"></Custom>
</InstallExecuteSequence>

What I have tried:

I read somewhere that for upgrade scenario this custom action gets called twice.I want to know how to prevent it getting called for the second time.