2 of 3 added 78 characters in body

Java 8, 313 300 bytes

import java.time.*;()->{for(int c=0,h=LocalDateTime.now().getHour(),m=LocalDateTime.now().getMinute(),i;;)if(c>30){c=0;String l="",u,d;for(i=0;i++<60;)l+="-";u=l.substring(0,m);d=l.substring(m);System.out.println((h<10?"0":"")+h+" "+u+"\n"+(h<10?"0":"")+(h+1)+" "+d);}else{c++;System.out.println();}}

This only updates every 30 iterations of the while loop. The other 29 iterations just print new lines.

Updated

Saved 13 bytes due to Kevin Cruijssen's help! Thanks!