Trustworthiness of autosomal DNA tests?

[reboun]

Is there any one who has taken an autosomal test twice?
If yes, did he/she scored the same as the first both on the commercial test and the GEDmatch?
Did he/she sent the second test with another name-surname combination so that the scientists would not know that person has taken another test before at the first glance?

If the answer is “yes” for all the questions above, we can say autosomal DNA tests are accurate. Otherwise, can we say autosomal DNA tests didn’t prove their reliability yet?

[Boudin]

I have taken the 23 and me test twice. I even used a different name and the results were identical. It listed my 1st test as being a twin with the 2nd.