In the Code , I found , a (actually more then one) Package, being declared in another Package.

I assume by that you mean you have a file with more that one package statement in it; and those package statements have different names after them?

Functions and methods become a part of whatever package is currently in force. So in this snippet:

package A;

sub fred { ... }

package B;

sub bill { ... }

package C; 

sub mary { ... }

package B;

sub joan{ ... }

package A;

sub cleo{ ... }
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There are five functions declared in three packages: A::fred() & A::cleo(); B::bill()/c> & <c>B::joan(); C::mary()

The number and ordering of package statement within a file is completely flexible; a subroutine belongs to whatever package (statement) is in force at the time of its definition.

It is also quite possible to split packages across multiple files; though the are generally less good reasons for doing so.