Dna results error, is it still accurate?‏?

I have a question to determine if I should take another paternity test. I took a test with a company with two different men but I noticed one of the alleles are different on the baby results on both test. First test her results were 13,13 on the second test (which confirmed the alleged father) were 9,13. And of course his allele was 9 which made all alleles match. Should this be a concern for me? or does it even make a difference? If it's a error does it mean that it could be more errors or is it a simple mistake that couldn't change the outcome of the test. The baby doesn't look anything like the confirmed father and I was wondering should i get another test done by a AABB credited company because the first company wasn't credited.