HashMap<Integer, myModel> aServiceHash = new HashMap<Integer, myModel>();
HashMap<Integer, myModel> rServiceHash = new HashMap<Integer, myModel>();

for (myModel ser : serAccepted){
    aServiceHash.put(service.getOriginalDate(), ser);
}
for (myModel ser : serRequested) {
    if (aServiceHash.containsKey(service.getDate())) {
        aServiceHash.put(serv.getDate(), serv);
    }
    else
        rServiceHash.put(service.getDate(), ser);
}