I have tried to find the answer everywhere but with no luck. Is it possible to connect 2 Marketo instances to 1 Salesforce?
If so, is it possible to do it natively or do we need to use 3rd party tools/API?
With the standard connector, this is totally impossible.
With an ETL, of course, this can be achieved. Look into Informatica, workato, ...
And with some custom API dev, this is possible too, but I would not recommend it.
In our org we're about to launch a second Marketo org connected to a single Salesforce org natively, so despite what you have seen above, we have been advised this is possible and are on track to do it. However, there are drawbacks - like you can only have Marketo MSI associated with a single Salesforce org.
I fact you are right, I read and answered to quickly. What's impossible is 2 SFDC with 1 Marketo.
The impossibility to have MSI on the 2 instances is not the only issue, though. You need to pay a lot of attention to how the data flows, in order to avoid having leads or contacts sync'ing with your 2 instances, otherwise, you will create a real data mess.
At the end of the day, it will only be workable if the data is clearly separated within the SFDC instance.
And as pointed out by Josh, there is quite a few threads on this already.
How did you solve the issue of multiple Marketo instances connecting data to a Salesforce org (e.g. lead, contact sync)? Is it possible to make one of them read-only?
With SFDC and Marketo, you can have a sync filter that manages which record goes from SFDC to Marketo.
I would recommend that you set some sync filters that are exclusive (a record can sync with either of the 2 Mkto instances, but not both). You will also need to have 2 distinct sync users.
Note: once your sync filter fields are set up, you will need support to activate them.
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