two blind men. There are no "discrepancies" between this account and those of Mar_10:46 and Luk_18:35. They describe three miracles on four blind men: one on approaching Jericho; one on leaving; two after He had left. See App-152.
Sitting. Not "begging", as in Luk_18:35.
by = beside. Greek. para. App-104. The others were at each gate.
passed by = is passing by.
mercy = pity.
Lord.App-98.
Son of David. Therefore Israelites, having a claim on Him as such. The fifth of nine occurrences of this title in Matthew. See note on Mat_1:1, and App-98.