How does your json look like? It should be something like this:
{
"url": "pool1.com:8005",
"user": "wallet_address",
"pass": "x",
"keepalive": true,
"nicehash": false
},
{
"url": "pool2.com:4332",
"user": "wallet_address",
"pass": "x",
"keepalive": true,
"nicehash": false
}
]
I also have a thread about mining with xmrig called [CryptoNight] CPU mining guide & coins that will get you a return and it may have some more info on what you're looking for
I don't really use multiple pools, seems like one pool works fine for me, but you need to look for good pools and not ones that frequently fail or are offline sometimes.