Opera 12.18 Update Problems

I use Opera 12.17 (portable only) and have not taken any of the Opera versions of 15 or greater which are offered by Apps/Check For Updates in the platform (12.2-7601).

The RSS feed told me that 12.18 is now available but the platform hasn't detected it as an available update for 'installed' apps. I downloaded the 12.18 paf.exe and used the platform's 'manual installation' but that placed OperaPortableLegacy12 alongside the pre-existing OperaPortable directory so it hasn't used my (extensively customised) configuration and settings. My platform menu now lists both 'Opera' and 'Opera Legacy'.

General or just me? Is this just the result of an unfortunate naming inconsistency? What is recommended as the optimal approach to get 12.18 to replace 12.17 while adopting all settings and in such a way that any eventual use of the portable Opera/Blink versions in parallel isn't compromised?

I guess it's not altogether impossible for Opera to release 12.19 as a security update at some time (although it now seems most unlikely) so this may just be a one-shot deal with manual intervention being an acceptable solution for myself and any other luddites encountering this.

Thanks