How to get common key and store value in comma separated in array

Here are the array

“articleCriteria”: [
{
“criteriaId”: 100,
“criteriaDescription”: “Fitting Position”,
“formattedValue”: “Front Axle Right”,
},
{
“criteriaId”: 100,
“criteriaDescription”: “Fitting Position”,
“formattedValue”: “Front Axle Left”,
}
]

iam running foreach loop because other data is also coming but for common key What i want is,

fitting_position = Front Axle Right,Front Axle Left