dual hosted email for 1 domain

I don't think it's possible.  You can have multiple MX records for one domain but that's generally configured at the same provider and multiple definitions are used only for redundancy not the way you wanted it.

No, you can potentially forward email from one to another, but one would have to respond to another domain name to do that.  You may be able to configure Gmail to check an Office 365 account, but what you're asking for is far from common.

Perhaps if you explain why you need this, we can come up with a better solution.

That seems rather redundant because it's still one email server taking in all the emails then passing it to another server.  If the primary email server is down, then there will no email going to the second email server platform as well.

It also sounds like a nightmare for the email administrator.  I can't imagine having to manage thousands or even hundreds of users for each platform this way.  But I agree, I think we need a better explanation why this specific setup is requested.

Yes you can.  G Suite allies dual delivery in which email sent to your domain can pass through to another service if the recipient is not on GSuite.

is it possible to have the Office365 system pass email to address not available to gmail
again goal is
1 email domain  lets say    xxxxx@abc.com
emaill address's in office65 and gmail with @abc.com
all email delivered/ received by office365 and if email box not in office365- forwarded to gmail system?

Yes, you can setup dual delivery where Office 365 is the primary.  the dual delivery is invisible to the senders/recipients in either direction.

Note this does not work with @gmail.com addresses.  Only with @abc.com addresses.  For the best invisibility, both O365 and G Suite should be setup with the same @abc.com domain.

Allen   do you have any documentation to reference or websites to reference to set this up  
Office 365 setup and googlemail system setup .
i was not sure i could have the same email domain name setup/registered on 2 different mail platforms

On the google side:
https://support.google.com/a/answer/6297084
and
https://support.google.com/a/answer/2685650

You only register the domain once.  The MX records only report to one service.  You setup a shadow domain that is used behind the scenes for the dual delivery.  The shadow domain is unknown to the users.