There are 3 ways for randomizing, a sequence (random), an option (randomly) and an action (randomize)

The sequence 'random'

HTML RESULT 
{sequence:random rows=25, minimal=10, maximal=50              } {$sequence} {/sequence:random}
28 36 46 14 34 11 44 28 25 29 39 40 11 11 36 38 50 40 15 42 28 18 47 16 36
{sequence:random rows=25, minimal=10, maximal=50, unique      } {$sequence} {/sequence:random}
25 23 13 20 39 46 26 15 41 12 27 43 42 35 47 17 38 10 28 16 22 19 34 36 48
{sequence:random rows=15, minimal=10, maximal=50, increment=5 } {$sequence} {/sequence:random}
30 10 25 20 45 25 15 20 30 15 25 40 25 10 50

The sequence option 'randomly'

Here the loop index is randomly set before the sequence is executed.

HTML RESULT 
{sequence loop,    rows=10, randomly, from=10, to=20} {$sequence} {/sequence}
19 14 14 15 15 19 18 15 19 11
{sequence power=2, rows=10, randomly, from=8,  to=16} {$sequence} {/sequence}
2048 2048 32768 8192 256 2048 16384 1024 16384
{sequence prime,   rows=10, randomly, to=1000       } {$sequence} {/sequence}
547 397 683 409 457 53 191 347 727 5

HTML RESULT 
{sequence rows=4, randomly } 
  {$sequence} 
{/sequence}
9177 6620 496 782
{sequence rows=4, randomly, from=10000000000, increment=10000000000} 
  {$sequence} 
{/sequence}
77800000000000 73170000000000 5310000000000 93230000000000

HTML RESULT 
{sequence from=10, to=20, push='mySeq'}
{mySeq randomly}         {$sequence} {/mySeq}
19 11 18 18 15 19 12 17 20 20 18
{mySeq randomly, unique} {$sequence} {/mySeq}
16 17 14 18 10 20 19 12 11 13 15

The sequence action 'randomize'

HTML RESULT 
{sequence from=10, to=20, push='mySeq'}
{mySeq}                                     {$sequence} {/mySeq}
10 11 12 13 14 15 16 17 18 19 20
{mySeq randomize                          } {$sequence} {/mySeq}
11 18 20 10 16 13 15 17 14 12 19
{mySeq randomize=5                        } {$sequence} {/mySeq}
17 16 12 19 13
{mySeq randomize=5, duplicates            } {$sequence} {/mySeq}
18 20 19 11 19
{mySeq randomize=5, orderly               } {$sequence} {/mySeq}
12 13 14 17 18
{mySeq randomize=5, orderly, duplicates   } {$sequence} {/mySeq}
12 13 18 18 19
{mySeq randomize=25                       } {$sequence} {/mySeq}
16 13 15 20 18 12 11 14 17 19 10
{mySeq randomize=25, orderly              } {$sequence} {/mySeq}
10 11 12 13 14 15 16 17 18 19 20
{mySeq randomize=25, atLeastOnce          } {$sequence} {/mySeq}
18 17 11 14 12 11 17 13 13 16 12 14 19 10 10 17 14 18 20 13 19 19 14 18 15
{mySeq randomize=25, atLeastOnce, orderly } {$sequence} {/mySeq}
10 11 11 11 12 12 13 14 14 15 15 16 16 17 18 18 18 19 19 19 19 19 20 20 20

The sequence 'random' - other usages of it

HTML RESULT 
{sequence random='75%', from=1, to=1000, push='myRandom2'}
{myRandom2 action='count'} {$sequence} {/myRandom2}
773

HTML RESULT 
{sequence random=4, from=1, to=1000, push='myRandom'}
{myRandom action='count'} {$sequence} {/myRandom}
260

Yes, it works

HTML RESULT 
{sequence random, randomly, randomize, maximal=1000} {$sequence} {/sequence}
496 849 206 645 6 862 350 48 774 404