Multiple port versions

[Vizion]

Just been doing a check on installed applications. 

pkg_info shows multiple installed versions of autoconf, automake, db & gnupg. viz:

autoconf-2.13.000227_5 Automatically configure source code on many Un*x 
platforms 
autoconf-2.53_3     Automatically configure source code on many Un*x platforms 
autoconf-2.59_2     Automatically configure source code on many Un*x platforms 
automake-1.4.6_2    GNU Standards-compliant Makefile generator (1.4)
automake-1.5_2,1    GNU Standards-compliant Makefile generator (1.5)
automake-1.9.6      GNU Standards-compliant Makefile generator (1.9)
db4-4.0.14_1,1      The Berkeley DB package, revision 4
db42-4.2.52_5       The Berkeley DB package, revision 4.2
gnupg-1.4.6_3       The GNU Privacy Guard
gnupg-2.0.1         The GNU Privacy Guard

I used partupgrade -aF recently when, on reconsideration, it would have been better to have done portupgrade -F on specific ports!

What is the safest way to remove the earlier versions?

Thanks
David