Some examples arise from reborrowing. For example, English pioneer was borrowed from Middle French in the sense of "digger, foot soldier, pedestrian", then acquired the sense of "early colonist, innovator" in English, which was reborrowed into French.
One example is the German semantic loan realisieren. The English verb "to realise" has more than one meaning: it means both "to make something happen/come true" and "to become aware of something". The German verb "realisieren" originally only meant the former: to make something real. However, German later borrowed the other meaning of "to realise" from English, and today, according to Duden, also means "to become aware of something" (this meaning is still considered by many to be an Anglicism). The word "realisieren" itself already existed before the borrowing took place; the only thing borrowed was this second meaning. (Compare this with a calque, such as antibody, from the German Antikörper, where the word "antibody" did not exist in English before it was borrowed.)
A similar example is the German semantic loan überziehen, which meant only to draw something across, before it took on the additional borrowed meaning of its literal English translation overdraw in the financial sense. Note that the first halves of the terms are cognate (über/over), but the second halves are unrelated (ziehen/draw).
Semantic loans may be adopted by many different languages: Hebrew kokháv, Russian zvezdá, Polish gwiazda, Finnish tähti and Vietnamese sao all originally meant "star" in the astronomical sense, and then went on to adopt the sememe "star", as in a famous entertainer, from English. In this case the words are unrelated (save for the Russian and Polish words), but share a base meaning, here extended metaphorically.