Would it be a waste to drink 2 servings of protein powder at once?

Generally, we recommend consuming 1-2 servings of your protein powder per day. This is going to depend on the rest of your diet and how much protein you consume in total. If you are eating a healthy diet though and including protein foods at your meals/snacks, usually 1 serving is sufficient at helping meet your protein needs.

There isn't much benefit in consuming too much protein for the day. However, if you consume a decent amount of protein at once, the extra doesn't necessarily go to waste. You shouldn't be as concerned about your protein intake at once, but more so over the entire day. 

Some people experience digestive issues from getting too much protein at once though, or in a day. If you consume two servings at once, it's more likely that you are probably eating too much protein in total for the day.