To find duplicate Titles in Evernote: (It's simple logic. It's a shame Evernote doesn't do this for us!!!)
Here are steps that work with Evernote version 7.14 on a Macbook Pro, also using Microsoft Excel for Mac 2011. This is a variation on the "use Excel" suggestion in this thread, but it is April, 2020, so this is more up-to-date than the suggestions below and will work with my current version of Evernote:
(1) Select All notes, then View/Top-List-View
(2) Click on first (or any) note, then Select-All (use menu, or [Command-A] on a Mac or [Ctrl-A] on a PC)
(3) Choose "Create Table of Contents Note" (you may need to scroll to see this option) (see 1st screenshot below)
(4) The "Table of Contents" (TOC) note will open. (Note that each row has a row number followed by a period. We will "clean" that in the the next step using Excel formulas.) Now: Click anywhere inside the note, then Select-All, then Copy (see 2nd screenshot below)
(5) Open Excel, then using columns A, B, and C:
(a) create the following titles: A1: "Original Title", B1: "Cleaned Title", C1: "Duplicate?"
(b) Paste the copy from the TOC into A2. All the titles should now be in column A.
(c) Enter or copy/paste this formula into B2: =MID(A2,FIND(".",A2)+2,LEN(A2))
(d) Enter or copy/paste this formula into C2: =IF(B1=B2,"DUPLICATE","")
(e) Now copy B2 and C2 formulas down to last row (in my case, that is row 725)
(see 3rd screenshot, with "Show Formulas" turned on briefly)
(6) Click anywhere in 1st row, then click or turn-on "Filter". Then click on Filter in C1, and select only "DUPLICATE" values. These are your duplicates. (see 4th screenshot)
1st screenshot:
2nd screenshot:
3rd screenshot:
4th screenshot:
pat holmes