When you say after the second day, does that mean you are washing every three days? Or, does it stink on day 2? I find that I really need to wash every two days to keep the smell at bay. Plus, with twins, you probably have more than enough diapers (around 24 at most) for a load in that time.
Honestly, I have never had a big stink issue with my newborn (no shock there) or with my toddler when he was in diapers. I think it really depends on you pail system and how often you wash. Is your pail open or closed? I tend to use an open pail (open garbage pail with a pail liner) or a highly vented one (garbage pail with the step on lid lined with a wet pail- the lid is never really closed). If you are using something that is all closed up tight, you will have a huge smell. When air is allowed to circulate, you won't have such a buildup of smell.
When you use baking soda, are you putting it on top of the wet diapers? If I had smell issues with my son's dipes, I could put some baking soda on top of the smelly diaper, and that would usually solve the problem. I also used a baby wipe at the bottom of the pail with some essential oils.
How long have you been using cloth? What diapers are you using? Did you buy them new or used? There are a lot of questions that could help narrow down your problem.