I suggest you examine the Tags of the 42 "extra" hits you get using the link. Do they have the "Based on Play" tag or not? Are they selected because other tags contain the words "Based" or "Play"?
I exported each set twice, once with the default "XML (Movies)" export plugin template and once with a modified template which only removed the encoding option. Both look the same when viewed with standard Microsoft Windows utilities (notepad, wordpad, PSPad text editor) but when I view it using Unix-like utilities, I find there are non-printable characters in the larger (hyper-link) set. The extra characters only show up in the tags field.
(We'll see what you on-line editor does with them. But I'll attach screenshots of the xml files in Emacs.)
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grep -Ei "[^/g]title|based on play" filename.xml|less
encoding="UTF8"
<title>12 Angry Men</title>
<tags>Murder, Jury, Trial, Jury Room, Restroom, All Male Cast, Heat Wave, Based On TV Movie, Watchmaker, Racism, Real Time,Ensemble Cast, Eyeglasses, Evidence, Photograph, Immigrant, Single Set Production, New York City, Legal, Advertising Executive, Witness, No Music, Switchblade, One Day, Death Threat, Stockbroker, Law, Architect, Salesman, Bank Clerk, Father Son Estrangement, Coach, Rainstorm, Based On Play, Number In Title, AFI Top 100-2007, MPAA Approved</tags>
<title>Amadeus</title>
<tags>Envy, Flashback, Musician, Asylum, Catholic Priest, Priest, Genius, Emperor, Classical Music, Loss Of Father, Wheelchair,1820s, Salon, Archbishop, Domineering Father, Maid, Prayer, Musical Chairs, Marriage, 1790s, Powdered Wig, Billiards, Jealousy, Buxom, Fainting, Marriage Proposal, Opera, Flatulence, Fireplace, Deceit, Lifting Person In Air, Mockery, Choking, Laughter, Talent, Pregnancy, Mediocrity, Cemetery, Primadonna, Crucifix, Piano, Candy, Child Prodigy, Italian, Father Son Relationship, Music Lesson, Intrigue, Loss Of Husband, Theater, Dictation, Madhouse, Blindfold, Funeral, 18th Century, Vienna Austria, Dog, Wedding, Tragedy, Composer, Confession, Censorship, Dwarf, Told In Flashback, Mozart's Requiem, Tony Award Source, Actor, Mother In Law, Murder, Kidney Failure, Male Frontal Nudity, Opera Parody, Masquerade, Mass Grave, Mask, One Word Title, Suicide Attempt, 1780s, Independent Film, Based On Play, Character Name In Title, MPAA R, AFI Top 100-1998</tags>
Unencoded
<title>12 Angry Men</title>
<tags>Murder, Jury, Trial, JuryáRoom, Restroom, AlláMaleáCast, HeatáWave, BasedáOnáTVáMovie, Watchmaker, Racism, RealáTime, EnsembleáCast, Eyeglasses, Evidence, Photograph, Immigrant, SingleáSetáProduction, NewáYorkáCity, Legal, AdvertisingáExecutive, Witness, NoáMusic, Switchblade, OneáDay, DeatháThreat, Stockbroker, Law, Architect, Salesman, BankáClerk, FatheráSonáEstrangement, Coach, Rainstorm, BasedáOnáPlay, NumberáInáTitle, AFI Top 100-2007, MPAA Approved</tags>
<title>Amadeus</title>
<tags>Envy, Flashback, Musician, Asylum, CatholicáPriest, Priest, Genius, Emperor, ClassicaláMusic, LossáOfáFather, Wheelchair, 1820s, Salon, Archbishop, DomineeringáFather, Maid, Prayer, MusicaláChairs, Marriage, 1790s, PowderedáWig, Billiards, Jealousy, Buxom, Fainting, MarriageáProposal, Opera, Flatulence, Fireplace, Deceit, LiftingáPersonáInáAir, Mockery, Choking, Laughter, Talent, Pregnancy, Mediocrity, Cemetery, Primadonna, Crucifix, Piano, Candy, ChildáProdigy, Italian, FatheráSonáRelationship, MusicáLesson, Intrigue, LossáOfáHusband, Theater, Dictation, Madhouse, Blindfold, Funeral, 18tháCentury, ViennaáAustria, Dog, Wedding, Tragedy, Composer, Confession, Censorship, Dwarf, ToldáInáFlashback, Mozart'sáRequiem, TonyáAwardáSource, Actor, MotheráInáLaw, Murder, KidneyáFailure, MaleáFrontaláNudity, OperaáParody, Masquerade, MassáGrave, Mask, OneáWordáTitle, SuicideáAttempt, 1780s, IndependentáFilm, BasedáOnáPlay, CharacteráNameáInáTitle, MPAA R, AFI Top 100-1998</tags>
[attachment deleted by admin]