Why $urandom not generate a random series

In reply to dave_59:

In reply to designer007:
You typically use a random seed each time you run a testcase. To debug a testcase failure, you use a specific number to repeat the same series of random numbers generated for that seed.

I try vsim -sv_seed random 2 times;


  task automatic test_rand();

    for(int i=0;i<32;i++) begin
      $display("rand test1 : %h seed: %h",$urandom, $get_initial_random_seed );
      $display("rand test2 : %h",$urandom(98));
      $display("rand test 10: %h",{$random()}%10);
      $display("urand test : %h",$urandom_range(32));
    end
  endtask

but rand test1 result is same , with diff seed

1st rst:

rand test1 : 99b8d01f seed: dbb145f2

rand test2 : cfccd4ba

rand test 10: 00000001

urand test : 0000000d

rand test1 : 7072cfdf seed: dbb145f2

rand test2 : cfccd4ba

rand test 10: 00000000

urand test : 0000000d

rand test1 : 7072cfdf seed: dbb145f2

rand test2 : cfccd4ba

rand test 10: 00000005

urand test : 0000000d

rand test1 : 7072cfdf seed: dbb145f2

rand test2 : cfccd4ba

rand test 10: 00000007

urand test : 0000000d

rand test1 : 7072cfdf seed: dbb145f2

rand test2 : cfccd4ba

rand test 10: 00000004

urand test : 0000000d

rand test1 : 7072cfdf seed: dbb145f2

rand test2 : cfccd4ba

rand test 10: 00000000

2nd rst:

rand test1 : 99b8d01f seed: 34b15e47

rand test2 : cfccd4ba

rand test 10: 00000001

urand test : 0000000d

rand test1 : 7072cfdf seed: 34b15e47

rand test2 : cfccd4ba

rand test 10: 00000000

urand test : 0000000d

rand test1 : 7072cfdf seed: 34b15e47

rand test2 : cfccd4ba

rand test 10: 00000005

urand test : 0000000d

rand test1 : 7072cfdf seed: 34b15e47

rand test2 : cfccd4ba

rand test 10: 00000007

urand test : 0000000d

rand test1 : 7072cfdf seed: 34b15e47

rand test2 : cfccd4ba

rand test 10: 00000004

urand test : 0000000d