I have accumulated DNA segment match information from ftDNA, GEDmatch, and MyHeritage. It is just recently that I've added MyHeritage DNA donors data, and I've found that the total number of matching SNPs, for a segment, are two to four times the value of GEDmatch and ftDNA (when comparing the same donors). Does anyone know the reason for this substantial difference?

Below is a one example of many...

From GEDmatch.com:

Chr Start Location  End Location     cM    SNPs  
3       23,760,064    29,187,906    6.2     931  
8       29,331,698    67,590,346   26.4   3,836 

From ftDNA:

Chr Start Loc   End Loc      cM     SNPs  
3   24060170    29187906    7.05     856  
8   29450700    68699024   25.84    3622  

From MyHeritage:

Chr Start Location  End Location    cM      SNPs  
3         24039380      29154358     7      2944  
8         29272247      67933838    26.3   14848