If a question A is a duplicate of a combination of two questions, what should I do? Should I flag it as duplicate of one of the two questions, and leave a comment?
The issue I have with comments is that that aren't meant to be kept forever: they may be deleted anytime, and users don't have access to their deleted comments. Even the source of non-deleted comments cannot be obtained.
Example 1: Neural networks: Differences between standard backpropagation, momentum and weight decay is a duplicate of the combination of Difference between neural net weight decay and learning rate and What is the intuition of momentum term in the neural network back propagation?.