Using the data setup from Eirikur and the data I added, the following works. Not knowing the state of your data, however, I can't promise anything.
SELECT
sd.SystemID
,ca1.IP
,ca2.MAC
FROM
dbo.SystemsRE sd
CROSS APPLY (SELECT LEFT(sd.IpAddress, PATINDEX('%,%', sd.IpAddress) - 1)) ca1(IP)
CROSS APPLY (SELECT RIGHT(sd.IpAddress, LEN(sd.IpAddress) - PATINDEX('%,%', sd.IpAddress) - 1)) ca2(MAC)
WHERE
patindex('%,%', sd.IpAddress) > 0;