Can there be two SharePoint 2016 Farms on same SQL Server?

If you are planning to do this, create separate SQL instances for each farm. I personally have run into issues with clients having two farms on one instance and not being able to quickly determine which database is on which farm is confusing and frustrating.

I know you may be doing this for licensing reasons, but just a heads up that you may experience slower than normal performance on your sharepoint farms.

Yes, you can share single SQL server with multiple farms, But it is recomended to avoid this in production.

• If SQL Server goes down for some reason then your both farm will be down.
• If their is issue on SQL server from one farm then troublshooting or correction of issues will hurt 2nd farm.
• If a heavy query running from one farm which consume all resources then you will see performance issue in both farms.

You have to keep an eye on the performance of the Sql Server and also make sure you have enough hardware which support the traffic from both farms. Also make sure you are using the unique name convention from both farm so that identification will be easy.