contrary to your diagnosis, the documentation says that use of the -file option does not cause this behaviour.

Hm. Here are my findings using the -file option:

[18:25:56.31] C:\test>dir test.png
26/05/2012  11:30             7,133 test.png

[18:26:17.25] C:\test>986015.pl
start
perl.exe                      6476 Console                    1     29
+,328 K
end
start
perl.exe                      6476 Console                    1     34
+,652 K
end
start
perl.exe                      6476 Console                    1     38
+,348 K
end
start
perl.exe                      6476 Console                    1     38
+,180 K
end
start
perl.exe                      6476 Console                    1     39
+,324 K
end
start
perl.exe                      6476 Console                    1     42
+,816 K
end
start
perl.exe                      6476 Console                    1     45
+,948 K
end
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