You can have multiple Perl versions on the Unix box, without any problems. I have 4 Perl versions out of which 3 are compiled.
When you install new Perl, the paths from old Perl won't be automatically added to the new Perl path, you should add these paths during installation.

Before installing the new perl make a list of paths which you want to add to new Perl search path

perl -le 'print foreach(@INC)'
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During the installation put the paths as listed below

List of earlier versions to include in @INC? [none] /usr/local/lib/per
+l/5.6.1 /usr/local/share/perl/5.6.1 /usr/lib/perl5 /usr/share/perl5 /
+usr/lib/perl/5.6.1 /usr/share/perl/5.6.1 /usr/local/lib/site_perl
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Once the shiny Perl is installed check out the paths, but I should note one problem here, you should install DBI modules for the new Perl, beacuse the .so files will be compiled with that Perl version, so the old DBI compiled modules are not compatible with new Perl.

Hope this helps