Database
[{"name":"name1","P31":10,"P32":2},{"name":"name1","P31":24,"P32":1},{"name":"name2","P31":1,"P32":1}]
Query
db.collection.aggregate([{$group:{_id:"$name",count:{$sum:1},sum:{$sum:{$add:["$P31","$P32"]}}}},{$project:{_id:0,name:"$_id",count:1,sum:1}}])