If it was loaded via require or use, yes, it is only compiled and executed the first time. It's import method will be called each time, allowing symbols to be exported into multiple namespaces.

# script.pl
use Module1;
use Module2;
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# Module1.pm
package Module1;
BEGIN { print("Compiling Module1\n"); }
use Module2;
sub import { print("Module1 exporting to ". caller() . "\n"); }
print("Executing Module1\n");
1;
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# Module2.pm
package Module2;
BEGIN { print("Compiling Module2\n"); }
sub import { print("Module2 exporting to ". caller() . "\n"); }
print("Executing Module2\n");
1;
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>perl script.pl
Compiling Module1
Compiling Module2
Executing Module2
Module2 exporting to Module1
Executing Module1
Module1 exporting to main
Module2 exporting to main
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>perl script.pl | sort
Compiling Module1              --> once
Compiling Module2              --> once
Executing Module1              --> once
Executing Module2              --> once
Module1 exporting to main      --> once per "use"
Module2 exporting to main      \
Module2 exporting to Module1   --> once per "use"
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