No, "melo" mean "badger". "ĝemelo" comes from the French, Spanish, and Portuguese words for twin, each of which in turn come from Latin "gemellus", the diminutive form of "geminus" https://en.wiktionary.org/wiki/ĝemelo I haven't seen "geĝemeloj" used much, but it does return some search results in Google
Your comment is interesting; Esperanto is not classified as an Indo-European but it is not because it's a constructed language. The vocabulary is obviously Indo-European; however the criterion that allows us to discriminate Esperanto from the IE languages is its morphology. IE languages are synthetic langages, and most of them are fusional, whereas Esperanto is an isolating language. I won't try to define it here because I'm not an expert and I'm not very comfortable with English but I highly encourage you to look it up! An easy example: in IE language (I believe) there is no direct connection between the first person and its derived forms (I -> my, me; ego -> meus, me; ich -> mein, mich; je -> mon, moi; etc). In Esperanto however, mia and min are directly derived from mi. Same goes with one -> first; unus -> primus; eins -> erst; un -> premier; etc but unu -> unua. So it's not directly because it's constructed that Esperanto is not classified as an IE language but because the way it is constructed radically differs from the way IE languages are constructed.
That's what I thought so actually guessed the word 'twins' before I looked at what it meant. I was a bit chuffed with myself for a minute there :) I am starting to work out more and more words before looking at the meaning when I hover my mouse over the word, so something must be sticking.
Yes. Other romance languages have similar terms (Italian: gemello, Portuguese: gêmeo) because the Latin word for twin is gemellus.
However, the Latin adjective for "paired" or "twin/twinned" is geminus. The noun twin is gemellus because in Latin, you can create nouns by adding the suffix -ellus.
So even if the word ĝemelo is a bit of a jump from the word gemini, it still has its roots from there; it just took a little journey to get here.