Brass-colored 5 öre coins from Sweden from 1972 and 1973 KM# 845

Hello to everyone here in the forum! While sorting through my Swedish 5 öre coins from 1972 to 1973, I noticed two brass-colored coins, one from 1972 and one from 1973, unlike all the other KM# 845 coins, which are made of bronze. The Numista catalog lists a brass trial coin from 1972 under N# 463706, but none from 1973. Could my differently colored coins actually be such trial coins, or could they have been given a brass-colored coating after being minted from copper? I would prefer not to scrape anything off the coins at first. The weight and size are the same for both coins, so how else could one distinguish or classify them as possibly genuine brass coins other than by their color? Perhaps one of you more experienced collectors can help me? Many thanks in advance, photos attached.

Your 1972 brass-colored 5 öre coin may be the documented trial strike (N# 463706), while the 1973 piece—uncataloged in brass—could be a post-mint alteration unless confirmed by alloy testing like XRF. Since weight and size match, color alone isn’t conclusive without metallurgical analysis.

To me it looks like coins that could be cleaned or been through some othe substance, but it could also be an unknown trial strike or similar.
Could you measure the exact weights and thickness for both 1972 and 1973 coins?