I found a few duplicates by running these queries:
##Events
SELECT event_description,count(event_description) AS cntEvents
FROM `Events`
GROUP BY event_description
HAVING cntEvents > 1
ORDER BY cntEvents

##Characters
SELECT character_name,count(character_name) AS cntChars
FROM `Characters`
GROUP BY character_name
HAVING cntChars > 1
ORDER BY cntChars

I started looking in to the duplicates and quickly determined that as obvious as it is that there are some incorrect entries, it is also equally obvious that this is not something I should be doing. So, here is a list of the duplicate events:

id -> Events -> # of occurences
52/53 -> Demeter looks for Persephone -> 2

55/650 -> Giants born -> 2

250 -> Some pursuing Colchians give up and settle -> 2

437/438 -> Hercules diverts the course of the river to clean -> 2

476/478 -> Hercules passes through with Geryon's cows -> 2

491/498 -> Hercules passes ... to get the golden apples -> 2		
	##is this too closely associated with 
		"Hercules passes through on his way to get 
		the golden apples, kills King Antaeus"
		(eventId: 493)  
		and 
		"Hercules passes through on his way to get 
		the golden apples, kills King Busiris and his 
		son Amphidamas"(eventId: 494)?

577/578 -> Hercules' sons leave Eurystheus and go to Ceyx aft -> 2

866/867 -> Oracle predicts victory for the Argives under Alcm -> 2

16/17/18 -> dominion awarded -> 3

280/281/282/283/284 -> Io still pursued by the gadfly -> 5		
	##is this too closely associated with 
		"Io, pursued by a gadfly from Hera, 
		comes to the Ionian gulf"(eventId: 279)?
	
447/448/449 -> Cretan bull wanders -> 3

229/230/239/240/242/248 -> Argo sails past -> 6		
	##is this the same as 
		"Argo sails through"(eventId: 241) 
		and 
		"Argo sails up"(eventId: 231)?
		
102 -> starting out for the Calydonian boar hunt -> 12

Duplicate Characters:

Characters -> # of occurences
Plexippus -> 2
Omphale -> 2
Archelaus -> 2
Semele -> 2
Hippocorystes -> 2
Hipponous (1) -> 2
Erechtheus -> 2
Argiope -> 2
Athamas -> 2
Actaeus (1) -> 2
Xuthus -> 2
Cercetes -> 2
Diocorystes -> 2
Molus -> 2
Antia -> 2
Deliades -> 2
Zethus -> 2
Amythaon -> 2
Opheltes -> 2
Aello -> 2
Nessus -> 2

And Places:

Places -> # of occurences
Locris -> 2
Nysa -> 2

Note that I made the mistake of attempting to edit the first two events myself:
Demeter looks for Persephone
and
Giants born
I may have screwed something up there, so if someone else could double-check that I haven't borked those events I'd appreciate it.