Maven unpack goal

Maven unpack goal

I encountered a strange problem while using Unpack Goal. Here how it is.
I have the unpack goal defined only in the parent pom and I have multiple
child test-projects(modules) which do not have unpack goal defined in
their pom's
Stage 1: I execute mvn clean install -Dskiptest=true to build all the
modules during this phase the unpack goal is executed and also I have a
version = RELEASE specified for the zip I wish to unpack. During the
unpacking phase version A.B.C is unpacked
Stage 2: Now when I want to execute each test I execute maven by
specifying the module which should be executed- Now why does maven again
executes the unpack goal from the parent and also it uses a different
version i.e. version P.Q.R is unpacked (which is the correct version)
Could someone throw some light on this issue. Q1 - Is this the correct way
of executing maven and if yes why is there such a difference during unpack
goal