RANBETWEEN accepts and returns integer values.

A
B
1
20:22
 A1: =RANDBETWEEN("20:18"*1440, "20:30"*1440)/1440
2
20:25
3
20:25
4
20:22
5
20:23
6
20:21
7
20:29
8
20:18
9
20:22
10
20:18