src/it/projects/mojo-tests/single-twice-in-multimodule-hierarchy/child1/pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <parent>
    <groupId>test</groupId>
    <artifactId>single-twice-in-multimodule-hierarchy</artifactId>
    <version>1.0-SNAPSHOT</version>
  </parent>
  
  <artifactId>child1</artifactId>
  <packaging>jar</packaging>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
  <build>
    <plugins>
      <plugin>
        <artifactId>maven-assembly-plugin</artifactId>
        <configuration>
          <descriptors>
            <descriptor>src/assemble/bin.xml</descriptor>
          </descriptors>
        </configuration>
        <executions>
          <execution>
            <id>single-assembly</id>
            <phase>package</phase>
            <goals>
              <goal>single</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
</project>