Double use of widget ID with context menu on draggable area

Describe the bug
I have an Area that is moveable by dragging it, and has a context menu. As soon as it's moved from the starting position, I get a big "Double use of widget ID" warning. This might very well be me doing something wrong, but I don't see what or how I can avoid it. The ID it's complaining about is not the ID of the area, but the ID of the response.

To Reproduce

use eframe::egui::{self, Area, Color32, Frame, Id, Pos2, Vec2};

fn main() -> eframe::Result {
    env_logger::init(); // Log to stderr (if you run with `RUST_LOG=debug`).

    let options = eframe::NativeOptions {
        viewport: egui::ViewportBuilder::default().with_inner_size([320.0, 240.0]),
        ..Default::default()
    };

    let mut pos = Pos2::new(40., 40.);

    eframe::run_simple_native("My egui App", options, move |ctx, _frame| {
        egui::CentralPanel::default().show(ctx, |ui| {
            let area = Area::new(Id::new("area"));
            let area_response = area.current_pos(pos).show(ui.ctx(), |ui| {
                let frame = Frame::default().fill(Color32::from_rgb(70, 70, 70)); // The frame is just to see better, it's not necessary to reproduce the problem
                frame.show(ui, |ui| {
                    ui.allocate_space(Vec2::new(100., 100.));
                });
            });

            if area_response.response.dragged() {
                let delta = ui.ctx().input(|i| i.pointer.delta());
                pos[0] += delta.x;
                pos[1] += delta.y;
            }
            area_response.response.context_menu(|_ui| {});
        });
    })
}

Click and drag the gray area a bit.

Expected behavior
No warning.

Screenshots

Desktop (please complete the following information):
OS: Linux. Reproduced under egui 2dac4a4f (current master).

Start by running the Rust reproduction in the issue body and tracing the interaction between Area::show, the draggable response, and response.context_menu. Inspect where the “Double use of widget ID” warning is emitted and add a regression test for moving an Area with a context menu; done means the reproduction no longer warns.