Two drop-down menus with same list to be plotted together

I’m making an interactive plot that features galaxy spectra and UV emission/absorption lines. I’ve already made one drop-down menu to switch between plotting the different 45 galaxy spectra, but I want to add another drop-down menu with the same list so I can plot two different galaxies at once. My thought is that the first galaxy spectra will be chosen from the first drop-down, and the second galaxy spectra will be over-plotted on top of the first based on the second drop-down selection. Is this possible?

You can use a multi-select dropdown to allow for more than one galaxy to be selected from the same dropdown: dcc.Dropdown | Dash for Python Documentation | Plotly

I tried this and was successful using Dash, but I now cannot export the full plot to html to use on a website. Are there any ideas on how to make this work?