1 Boliviano KM#205

I went to Bolivia in 2006 and brought back some coins. Now that I've started identifying the coins, I noticed an anomaly with the 1 Boliviano (KM#205). I have two coins (1991 and 2004) and both are identical except for several subtle differences. The font for the 1991 coin is bolder on both the obverse and reverse and the "1" is smaller than that of the 2004 coin. Additionally there seems to be more detail on the leaves on the reverse of the 1991 and there are several subtle differences in the design of the ensignia on the obverse. It looks like the design for the newer 1 Boliviano (KM#207) but with the older text still. Should this be a KM#205.1 and KM#205.2 deal?

I also noticed a similar difference in the 50 Centavos coin (1987 and 2001).

Minor differences don't always have another KM# number.

Yes, there are minor differences in the design of the coat of arms, the leaves and the circle. All coins from the same year but different face values have the same design. For example only the 2008 coins have these strange horizontal lines in the sky in the inner part of the coat of arms.
I will add a comment about the different designs regarding different years but no new numbers.

Costa Rican coins have similar minor vatiations from year to year, but are consistent within a year's issue.  Probably originates from recutting dies for every minting, or from switching mints for each purchase order.  Please take a look at the Costa Rican listings to see how this kind of problem is handled.

The difference can clearly be seen in the position of the word '"BOLIVIANO"
in the older coins (small 1) it is placed in the middle of the coin, and the top of "BOLIVIANO" aligns with the top of the 'U' of union
in the newer coins (large 1) the text is placed lower than halfway and the top of "BOLIVIANO"aligns with the middle of the 'U' of union

similar for the 50 Centavos, the word 'CENTAVOS" in the middle of lower than the middle