Two variants of KM#42 , Mahatma Gandhi 1969 commemorative?

Hello!

While adding a few Indian coins I noticed that two of 1969 Mahatma Gandhi coins I had were very different from each other.. the information suggests that the coin had some variations.

The rim seems to be different.
Is a variation or a die error?
KM 42.1 and KM 42.3 maybe.
Any help appreciated.

Looks, like the brighter one is of Calcutta mint (no mintmark) and legend is close to the rim, that is the first line in the year distribution of the article
https://en.numista.com/catalogue/pieces1621.html
The darker coin bears the mintmark of Mumbai ♦ under the numerals of face value. For the legend on the side with face value is far from the rim, it is not the fourth line of the article. For there is no difference in portraits of the leader from your photo and the photo of © Joseph Kunnappally in the Numista article, but the photo of © Joseph Kunnappally is of the proof coin (the last line in the article), it is left one option only:
The fifth line in the year distribution.

Note about sides of the coin. It is a bit tricky in this case, for the side with the political leader is the Obverse by definition (at least in this way I must teach numismatics to students), despite of this it was named Reverse by the United States' propaganda.

Note about the modified portrait. It is worth to ask the Numista community to present an image of this type, so been in the article it will make the attribution easy.

Thanks a lot!

Is this a mint variation?

It is good question.

In this case we have different mints. This fact is already enough not to expect from them any similarity at all. Yes, we may make a research:

Is it possible, that these mints used exactly the same 'mother-die', which was sent to them from one place.

In many cases it is of theoretical interest, which lays apart of most collectors interests. So you are welcome to conduct such small investigation and make conclusions.