karlgoethebier is right in the sense that you may not have now two Perls but over time you did have two or more Perls via the upgrades. The error message tells me that List::Util has not been recompiled and linked with the new Perl after the Perl exe upgrade. When an upgrade happens, then all modules which have XS/C components must be re-compiled and re-linked to the new Perl. But often the list of said modules is incomplete (perhaps because we usually do not upgrade via the system's package manager but Perl's package manager). So (re)installing List::Util (and all Perl modules) via the system's package manager will most likely fix the problem (*). Be warned that forcing a Perl upgrade may break some things in your system because GNU/Linux uses Perl for housekeeping and certain versions need certain Perl versions etc. The solution is perlbrew. It will allow you to have as many Perls as you wish without tampering with system's Perl at all.

Edit thanks marto: *) If you can't use the system's package manager then you can use cpan-outdated to list all outdated modules and possibly pipe its output to cpanm for reinstalling. For example: cpan-outdated | cpanm -L ~/perl5 --reinstall.

Edit2 anonymous monk below (Re: Symbol lookup error for my ~/perl5/lib/perl5) makes a valid point that cpanm may not work because of this incompatibility and suggests a workaround