I've seen that with older road signs here, you can see the 25 mph under the now faded 40 km/h overlay. The overlays where put on when we converted the signs to metric in the late 70s.
The old sign was painted on with Duco paints, whilst the new sign is done with either a self adhesive sticker or a paper printed sign stuck on with a waterproof glue.
Yep, the road signs were all in imperial before '77, here's what the old signs looked like. And here's a old imperial speed limit 45 sign...the metric signs were always in tens and would say 70 instead.
Here's some more info on it and there's a pic of one of those pasted over 25 signs I was talking about before.
And funny thing is even though we're metric now, if you go in Home Depot all the lumber is still measured in imperial, and some food and drinks are packaged in the old imperial sizes but with metric only or dual metric and imperial units(like 1lb of butter being sold as 453g)
And funny thing is even though we're metric now, if you go in Home Depot all the lumber is still measured in imperial, and some food and drinks are packaged in the old imperial sizes but with metric only or dual metric and imperial units(like 1lb of butter being sold as 453g)