Perth Zoo, Western Australia has/had two families of Northern White Cheeked Gibbons from 1999 onwards; the first pair (& at times offspring) and the Australia/New Zealand regions longevity record holder Philip (b c.1972 and been at zoo since October 1974) and his second partner live on an island in the zoo's main lake. The second pair (& at time offspring) live in a 30m x 10m aviary like exhibit in the north east corner of the zoo between the Sun Bears and Red Panda exhibits.
The Zoo also has/had a group of Black and White Ruffed Lemurs living on another lake island but also a second group of B+W Ruffed Lemurs living in one of the exhibits in the zoo's 'Lesser Primates' precinct on the other side of the zoo.
For a very short time in the mid to late 1990s there was a second smaller in number group of Meerkats in the zoo's African Savannah precinct that were apparently individuals who were kicked out of the main group, at one point one of the Meerkats from this much smaller group dug a tunnel into the next door exhibit inhabited by a Serval named Mungo who consequently ate the poor Meerkat and as a result the rest of the Meerkats were moved (to off public display holdings I believe). There were about four exhibits (Hunting Dogs, Cheetah, Scimitar Oryx, Mungo the Serval) between the first group of Meerkats and the second group.
Apparently there was for a brief time (I haven't been back to Perth Zoo since 2006 so this is just from trying to keep up to date with news) another double up of Meerkat troops in the zoo's Savannah precinct in the last ten years (again for a short time I believe) but by then the descendants of the first troop had moved from their old exhibit opposite the White Rhino exhibit to a new bigger exhibit (former Spotted Hyena exhibit though renovated beyond recognition with a path for visitors into the exhibit space with 1m (approx') high glass for viewing the Meerkats. The second group (again wonder if they were exiles from the main group) were again in the same second exhibit (though I wonder if the zoo had cemented under the sand now to avoid tunneling escapes) and their neighbours to the left were now a couple of Fennec Foxes as Mungo the Serval died in 2003 (aged 18, I loved that Serval thats why its easy to keep mentioning him by name and with details lol but back to the same species relevence), by this time there was only two exhibit between the two Meerkat groups. First was an indoor nocturnal exhibit in a mock rock cave that rarely had any animals living in it (until recently had a Madagascan Boa which has since died but at the time of the second Meerkat double up it probably wasnt in use) and which was on the other side of the path (the Rothschild's Giraffes and Grant's Zebras) and visitors could easily choose whether to go look at the main Meerkat group first instead of the Giraffe/Zebra (there was only about a 40m walk between the the visitors viewing of the two Meerkat groups at that time).