The humour is the same. They both have serious plots and geeat performances but out of nowhere you are laughing with tears in your eyes.

Same Same but different ???
If you need You Are My Secret summarised, dumb downed and sugar-coated, the n watch this.

Go Princess Go was an earlier work of one of The Double's directors. It has the same artistic theatrical style of The Double.
Even though The Double is altogether a better drama, you might try Go Princess Go to see the same level of drama and shock factor.

They both feature the adult fl going back in time to relive her high school days and attempts to change their futures by making different choices in the past. They both involve time jumps from the future to the past multiple times and attempts to prevent someone from dying. Lovely Runner should heal the broken heart Shining for One Thing, causes.

The two dramas have very different storyline but are similar by both having: Stable couple relationships, Supportive ML, Strong ML, Smart FL, Slowburn and minimal skinship (physical dispaly of affection).