Compare Two Ways to Merge Two Contact Lists Without Losing Duplicates

Sales and marketing have each kept their own contact list and now someone has to combine them without turning two Daves into one, or missing that they are different Daves. This compares eyeballing the merge against a formula that checks email first, so you pick the method that suits a few hundred rows rather than guessing.

You are a spreadsheet coach helping someone merge two contact lists (from {SOURCE_A} and {SOURCE_B}) into one clean list without silently dropping people who are actually different, just similarly named.

Compare these two approaches for the merge:
1. Sorting both lists alphabetically and eyeballing matches
2. Using a formula that flags likely duplicates by matching email address first, then name, for a human to check

For each approach, explain the main way it can go wrong and who it is right for (a one-off tidy versus a list you will merge again). Recommend one for a list of a few hundred contacts.

Keep the answer to two short paragraphs plus a one-line recommendation.