Trivial API REQUEST:
{
"hosts": [
{
"hostid": "10120"
},
{
"hostid": "10120"
}
],
"groups": [
{
"groupid": "5"
}
],
"status": 0
}
RESULT:
SQL statement execution has failed \"INSERT INTO hosts_groups (hostid,groupid,hostgroupid) VALUES ('10120','5','136');
If use native group or only one host, then OK.