1984 D Lincoln Memorial Cent - Mintmark Variety?

I believe up until 1990 the mint mark was applied to the die by hand, so they wander around a little.

You mean, that mintmark was applied to every working die by hand? That means, every die would bear its own unique position of mintmark.
The mintages in 1980s were over 4 billion every year. Therefore, thousands of dies were produced every year. And they all were marked by hand? If so, there would exist thousands of mintmark locations on the coins of each year, and it would be hard to find two simmilar coins. Is it really so? I don't have too much US coins, but easily found some similar pairs of coins before 1990. And only these Two Cents 1984 D were different.
The Red Book shows some varieties like "large date" and "small date", "double mintmark", "D over S", and so on, but does not mention mintmark position at all. Why? It is clearly seen that these my Two Cents are really different.
I'm interested, because such varieties are very popular in Russia on modern coins - coins of some certain years have one common variant of mintmark M (Moscow) location, easy to find, and several rare variants. And three types of coins were found without mintmark. Some variants are very hard to find, they are priced very high.

coins2001 - Your understanding is correct that every mintmark was placed into each individual working die by hand until 1990. The reason these don't have particular value is because there has never been an interest in them among the general collecting community unless the mintmark is place outside the normal area for a mintmark - which on a Lincoln Cent is under the date, in front of the vest, and within the rim. Beyond that anything goes.

Your mention of mintmark omissiom is important here. In 1990 some of our San Francisco (S) mint cents were minted without mintmarks. Those are extremely valuable and rare. In 1922 all cents were minted in Denver (D) and should have had D mintmarks. Some, however, for one reason or another did not have mintmarks, and the value of such coins are currently through the roof.

The exact position, however, of a mintmark has never been an issue here.

coppercoins, I posted my reply before reading yours. Thanks, I learned something new.
I'd like to ask the last question - what had happened in 1990?

If the mm is not touching a design element, it is considered a normal placement. As stated, prior to 1990, they were applied by a hand.

Since each die would stamp on average many tens of thousands to hundreds of thousands of coins, and a lot of those coins would end up in the same geographical areas,it is pretty common to find coins of the same date with the mintmark placement the same.

Also as for different placement on same date they are all over the place before 1990. These two are both 1960d and you can see that the one on the left has the MM much closer to the 9 then the right one.