Run javadoc on the following simple source, and look at the resulting package table. "p" shows up twice.

$ more $(find play/duplicates/src -name \*.java)
::::::::::::::
play/duplicates/src/C.java
::::::::::::::
package p;
public class C { }

::::::::::::::
play/duplicates/src/module-info.java
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module m {
    exports p;
    opens p;
}