Android ArrayAdapter performFilter clean all values

I have an arrayAdapter which is filtered with a SearchView. The filtering is working, but my problem is that it also clean another entity which shouldn't be edited:

public class LvSecurityAdapter extends ArrayAdapter<Security> implements Filterable{

    private ArrayList<Security> allSecurities;
    private ArrayList<Security> securities;
    private Context ctx;

    public LvSecurityAdapter(Context ctx, int tvResourceInt, ArrayList<Security> securities) {
        super(ctx, tvResourceInt, securities);
        this.securities = securities;
        this.allSecurities = securities;
        this.ctx = ctx;
    }

    @Override
    public int getCount() {
        return this.securities.size();
    }

    @SuppressLint("InflateParams")
    @Override
    public View getView(final int position, View view, ViewGroup parent) {
        LayoutInflater inflater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        view = inflater.inflate(R.layout.row_lv_security, null);

        Security security = securities.get(position);

        final ImageView img = (ImageView) view.findViewById(R.id.ivTipologia);
        final TextView tvName = (TextView) view.findViewById(R.id.tvName);
        final TextView tvDescription = (TextView) view.findViewById(R.id.tvDescription);
        final TextView tvTags = (TextView) view.findViewById(R.id.tvTags);

        img.setBackground(ctx.getDrawable(security.getTipology().getImageId()));
        tvName.setText(security.getName());
        tvDescription.setText(security.getDescription());
        tvTags.setText(security.getTag());
        return view;
    }

    private void notifyThis(ArrayList<Security> values){
        securities.clear();
        securities.addAll(values);
        this.notifyDataSetChanged();
    }

    @Override
    public Filter getFilter() {
        return new Filter(){
            @Override
            protected void publishResults(CharSequence constraint, FilterResults results) {
                notifyThis((ArrayList<Security>)results.values);
            }

            @Override
            protected FilterResults performFiltering(CharSequence constraint) {
                FilterResults results = new FilterResults();
                ArrayList<Security> securitiesFilteredLocal = new ArrayList<>();
                for (Security s : allSecurities){
                    if(s.getName().toLowerCase().contains(constraint.toString().toLowerCase()) ||
                            s.getDescription().toLowerCase().contains(constraint.toString().toLowerCase())||
                            s.getTag().toLowerCase().contains(constraint.toString().toLowerCase())||
                            s.getTipology().getName().toLowerCase().contains(constraint.toString().toLowerCase())){
                        securitiesFilteredLocal.add(s);
                    }
                }
                results.count = securitiesFilteredLocal.size();
                results.values = securitiesFilteredLocal;
                return results;
            }
        };
    }
}

As you can see I have two entities on my constructor: securities and allSecurities.

securities is the entity which fills the adapter and the one which is filtered.

allSecurities is an helper entity. I need it because after filtering, if I delete some characters from the filter, I need to retrieve all entities and perform the filter again, but when I filter my results and I save them into securities, it also put the filtered result into allSecurities.

My question is pretty simple: why it override my entity if it is never accessed for edits? and how can I avoid the overriding?

Thanks all