"Holland" is a region within the Netherlands...I thought you'd know that ;)
In English-speaking countries it is common (though ultimately incorrect) to refer to the Netherlands by the name of this smaller region. In the same way, we often call the United Kingdom "England" and used to refer to the Soviet Union as "Russia." Given this fact, it's not surprising that these two entries should appear on a list...it's a mistake, but an understandable one.
All that said, I should check to see whether the more local-minded user can select his nation rather than his state, e.g. can you identify yourself as Welsh rather than a citizen of the UK? Here in the US, we have the commonwealth of Puerto Rico, whose citizens can boast their own Olympic teams and whose flag is the source of much pride.
Can anybody tell me why there are two countries on chess.com Holland and the Netherlands. What is the difference