Why do I get several records in select using random function in postgres?

This is my query:

SELECT id, geom from lars.punkt where id = (floor(random () * 99))::integer;

This is the result:

id    geom
40  "010100000000000000000010400000000000000000"
80  "010100000000000000000020400000000000000000"
88  "010100000000000000000020400000000000002040"

What is happening? I can also get 2 lines or zero lines.

I am expecting 1 line.

Is it the database which is "slow" or the code?