I believe it is important to separate good failures from bad failures. Good failures happen when, even though you made the correct decision, you still lost. Bad failures happen because you made bad decisions, or worse, didn't make a decision at all. Although the two feel the same, they have a completely different long-term impact.
I'm a novice poker player. One of the first things I learned was that there were good wins and bad wins. Good wins were because you had a sound strategy of betting where the odds were in your favor. Bad wins happened when you just got lucky. Going all-in on a 2-7 off-suit might win the hand. But it doesn't mean you're a good poker player.
Mentally separating good failures from bad failures takes work. Poker is a simple game where the laws of probability are cleanly defined. Real life is a lot messier. It takes more effort to decide which failures were because of a bad decision and which were just the unintended side-effects of the best choice available.
Although it can be difficult to separate the two, there are benefits to making two piles instead of just one. By separating the two types of failures, it is easier to persevere through good failures. It may hurt to have your Business proposal shut down for the fifteenth time, but it isn't necessarily a bad failure.
By separating the two, you can also avoid more bad failures. If you fail because of laziness, indecision or poor planning, you can quickly correct those in the future. Knowing the difference between good and bad failures keeps you from repeating stupid mistakes.