As Jon_Lindeheim and you stated, this should work fine. so i recreated everything from scratch as follows:
I have two WCF services that had the same base address and a different relative URI
i.e.
for service 1:
<add baseAddress = "net.tcp://computername:7777/" />
...
<endpoint address = "/service1" ... />
and for service 2:
<add baseAddress = "net.tcp://computername:7777/" />
...
<endpoint address = "/service2" ... />
I was not aware that base addresses must be different not just the eventual absolute URI.
so the following works fine: for service 1:
<add baseAddress = "net.tcp://computername:7777/service1/" />
...
<endpoint address = "/service1" ... />
for service 2:
<add baseAddress = "net.tcp://computername:7777/service2/" />
...
<endpoint address = "/service2" ... />
(why the first erroneous way still works when all is in one process, i think it's related to the way port sharing routes the traffic on a process based way).
Thanks again