hey! my iphone is not counting steps from my both phones ( x and 13) both show different steps.. i want them to merge.

Hey! So i am using 2 phones (X and 13) and they are not merging the fitness data. I went for a walk carrying X and it had 4k steps and i used the other 

phone 13 the rest of the day and it had 2k steps. Why did not the data merge? It is very annoying and manually adding the steps is not a good option because the fitness ring does not close then (because that counts kcals not steps). I have tried restarting my both phones and i have checked the devices on the health app, both are connected.

Any help would be appreciated, Thankyou in advance!