When releasing from a parent POM, won't all its modules have the same release version and dev version as this parent?

Maven Release Plugin will prompt for each project's version.

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How can I release a parent POM without releasing all it's modules?

You need to pass the -N flag to Maven and configure the Release Plugin to pass the -N flag on it's forked builds with the -Darguments flag.

Here's an example:

mvn -N -Darguments=-N release:prepare
mvn -N -Darguments=-N release:perform
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