It doesn't matter that they did not destroy some "list" because they should not have been able to build one with actual names of players in the first place if the tests were given anonymously as agreed upon. You'd simply have an anonymous list of pos/neg results:
Anonymous1: neg
Anonymous2: pos
Anonymous3: pos
Anonymous4: neg
.
.
.
Anonymous1: neg
Anonymous2: pos
Anonymous3: pos
Anonymous4: neg
.
.
.
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