I got the same results on SuSe 9.2 using v5.8.5 built for i586-linux-thread-multi. However, I also recieved the following warning:

Name "main::SAVED_STDERR" used only once: possible typo at test.pl lin
+e 7.
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Now, when I run the code posted by ikegami above, i get the following output:

testing stdout capture 1
testing stderr capture
testing stdout capture 2
[download]

Hmm.