I have two Adsense account, and a single website. There are a few subdomains.
It’s possible to use multiple Adsense Ads on one single website. But in some cases, if any violations are found, both Adsense accounts will be flagged (and might be suspended).
Before adding the same, make sure that the site is multi-author and each author’s ads will not coincide (or display on the same page).
Moreover, it is a tedious process that requires a lot of background task to get approved from Adsense. If you believe it is worthy, then go with it.