Different behaviour between linux and windows regarding SNASPHOT dependencies packaging

I've used the following descriptor to pack all the transitive dependencies of a project in a single tar.gz:

<?xml version="1.0" encoding="UTF-8"?>
<assembly>
    <id>bin</id>
    <formats>
        <format>tar.gz</format>
    </formats>
    <dependencySets>
        <dependencySet>
            <outputDirectory>lib</outputDirectory>
            <includes>
                <include>*:*</include>
            </includes>
            <unpack>false</unpack>
            <scope>runtime</scope>
        </dependencySet>
    </dependencySets>
</assembly>

I've got different results if running mvn assembly:assembly in linux or in windows, regarding the SNASPSHOT dependencies.

In linux the SNAPSHOT dependencies jars are of the form:
depName-1.4-beta-6-SNAPSHOT.jar

In windows the same SNAPSHOT dependencies jars are of the form:
depName-1.4-beta-6-20090114.094414-1.jar

Best regards,

Enrico