Merge tables multiple servers (using ODATA)

Hi, everyone

The scenario is this:

• Two tables in two databases from two different servers (Table 1 and Table 2).
• I have used ODATA to connect with datas (ODATA Table1 and ODATA Table2).
• I have done two reports using Power BI Desktop in every server (Report Table 1 and Report Table 2). Then I have published to power bi with same account.

The questions are:

• Do I have to install two on-premises gateaways (one per every dataset) to refresh data or is enough using only one?.
• Can I merge data in Power BI Service in some way?.

We are using Power BI Pro

Thanks,