If you've paused, reset or changed the clock you will affect the aging process of these tamas. So even if you started both V3s at the same time, if you have changed stuff on one it will not age at the same rate. But it will still age.
Which character do you have on the V3 at the moment? When it evolves / ages will be different depending on whether you have a toddler, teen or adult and it will help you work out what stage your tama has reached reached in it's evolution and how long you will have to wait before the next evolution.
Try not to pause, reset / download as you will definitely slow the evolution.
You should be able to marry them. If one of the V3s reaches adulthoood you can simply pause it until the other V3 character catches up and has become an adult too.
Hope this helps. A lot is guess work as you haven't given much info about your V3s to help make a more accurate prediction