It's understandable - their names in their respective languages is "Slovenija" and "Slovensko" which is relatively similar. Tougher still is discerning Slovenia and Slovakia in spoken Czech or Slovak - "Slovinsko" vs "Slovensko" - though context tends to help here :)
Another fun thing I have heard multiple times is that ordering electronics from China to "Ljubljana, Slovakia" somehow makes it from China to Slovakia and then Slovenia without going through customs in any of those two countries.
Does anyone know why this would be? Or maybe is it just pure luck?
I imagine that creates a special bond over time. :) In Sweden there are two municipalities who shared a website for a long time. Ironically? the HÅBO muni got to keep http://HABO.se while the HABO muni had to settle for http://HABOkommun.se