Upvote:0
You can apply to any number of visas at a time. However, most countries will require your passport while processing a visa. This would make it difficult to simultaneously apply to two visas, but you could apply for a German visa now, and then one for the Netherlands next.
Upvote:1
You need two different visas for two different purposes. So you can either apply for a work visa in Germany, or one to study in Amsterdam.
For each, you will need to submit your passport; and each require a different set of requirements in terms of paperwork. Therefore, you cannot apply for both at the same time.