xmrig won't mine on two pools in parallel, it will switch to the other pool if the first one fails.
How does your json look like? It should be something like this:
"pools": [
{
"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.