Suzanne - my own branch of Hollanders indeed came from Romania, but the Hollander name does not seem likely to have originated there. I have read two explanations for the family name, one being that it was adopted by Jews that lived in "Oleder" or Dutch areas set up for Dutch farmers to live in Poland, mainly along the Vistula river, and another version I have heard is of a Hungarian Hollander who says that his ancestors were in fact Sephardic Jews who fled to Holland from Spain and took the name "Hollander" as a sign or their origin from Holland when they moved into Eastern Europe. An interesting explanation of the background to Hollanders in Poland is here: http://www.polishroots.org/history/dutch_populace.htmhttp://www.polishroots.org/history/dutch_populace.htm
There are plenty of Dutch people who also have the name just because they like it. If your Hollanders are of Jewish background, there are a number of theories about but looking at Jewish genealogical resources, it seems most probable that the name was adopted while living in Dutch villages in Poland. The Romanian and Russian Hollanders appear to have moved to those towns from Poland and thereabouts following opportunities set up to encourage Jewish migration around the early to mid 19th century.
All the above said, there appear to not have been that many Romanian Hollanders, so if you can find any links to there, we could well be related. However, fact is that most Jewish people seem to have taken surnames relatively late (some not until the 19th century) and in a very random manner, and had no problem with frequently changing those names, so the exact origin of the name might not be traceable.