Two Germanys

To make the plural of a word ending in y:

If there is a vowel (a,e,i,o,u) before the y, add s

tray, trays
valley, valleys
boy, boys
monkey, monkeys.

If there is a consonant before the y, remove the y and replace with ies

baby, babies
pony, ponies
lady, ladies
family, families
Germany, Germanies

I believe it is correct to follow the common rule of plurals in English, and render more than one Germany as Germanies. A quick web search showed such a usage.

So Contrex and Setanta say 2 different things. I am a bit confused.
I can't know how to made plural countries.

No they don't, they're both saying use Germanies.

We say the same thing. I gave a rule to decide whether to use the -ys ending or the -ies ending. It seems you did not understand it. The name of a country is no different from any other word in this respect.

With a vowel before the final letter 'y': Norways, Uruguays, Paraguays, Turkeys. With a consonant before the final letter 'y': Germanies, Italies, Hungaries.

A noun changes the y to ies - countries,
With names the y remains a y.
So it would be Germanys.
She got two Grammys.
There are teo Billys in my class

Hmm... interesting.. I might agree about personal names e.g. two Marys, although I have seen Marys and Maries, and I am willing to concede two Grammys. However usage seems not to be fixed, and I assert that the "-ys after a vowel/-ies after a consonant" rule is within the bounds of acceptability. Especially when writing about Italy, it would seem! Below I submit some (not very scientific) evidence.

Google (using quotes to get exact match):

"two Germanys": 104,000 results
"two Germanies": 63,400 results

Example: Germanies may refer to Germany while it was divided into multiple states (...) (Wikipedia)

"two Italys": 3,500 results
"two Italies": 138,000 results

Example: Joseph Luzzi takes the title of his brief, bittersweet new book, “My Two Italies,” from Shelley, who, in a letter of 1818, distinguished between the Italy of “the green earth and transparent sea, and the mighty ruins” and the human reality he encountered there: “The one is the most sublime . . . the other is the most degraded, disgusting and odious.” (NY Times)

"two Hungarys": 347 results
"two Hungaries": 673 results

Example: ...the upshot was that he tried to organize the economic and social foundation for the Kulturkampf between the two Hungaries that existed in his mind (Political Transformation and Changing Identities in Central and Eastern Europe, edited by Andrew M. Blasko, Diana Januauskiene)

Also, "The two Hungaries" (spelled thus) is how historians refer to the two mediaeval Hungarian kingdoms united in 1102 AD under Coloman.

"two Picardys": 1 result
"two Picardies": 0 results

"two Lombardys": 5 results (mostly about Lombardy poplar trees)
"two Lombardies": 175 results, mostly the European region: "

Example: In many cities of the two Lombardies (as Riccoboni informs us) the spring of the year is allotted for comedies" (The Tragedies of Sophocles, from the Greek. Trans. Thomas Francklin)

So you see there is no simple rule for countries/locations.

Looked in my grammar and that how I got the answer.
Two Marys and two Maries is tricky. It could be two girls with the name Marie.
In German and the Scandinavian, country is land and countries is länder.
The name of a country in this case Deutschland or Tyskland remains in singular even when divided into two.

Grammar books often give "rules" that do not match reality.

Yes. Or not.

Savina Yannatou and the Primavera en Salonico Ensemble present the Virgin Maries of the World, a collection of popular and folk songs, hymns, encomia, eulogies, lamentations, carols, excerpts from popular masses (missa) all dedicated to the universal figure of Virgin Mary

the text only condemned the view that there was more than one Magdalen, without saying how many Maries there were (Jacques Lefèvre D'Etaples and the Three Maries Debates by Jacques Lefèvre d'Étaples)

Mary, the mother of Jesus, and the many “Maries” within the local community who have similarly experienced loss

Today we are going to find out how many Maries were mentioned in the Bible and what was the role of very one of them.

Here I agree with you. There are four Virgin Maries in our church.
But four Maries in my class can be a mixture of Mary and Marie, Correctly one would than have to say. There are three Maries and one Marie in my class.

You have choices. In order to be economical and at the same time to avoid ambiguity, you could write "three Marys and one Marie". In speaking no issue would arise since the two names are pronounced differently. You could avoid the issue by writing "Two girls named Mary and one named Marie".

Incidentally Din there's a trend away from comma except where its omission might drastically alter meaning

Both are used. A quick search suggests that "Germanys" is preferred in US publications, while "Germanies" is preferred in British publications.
For example:
US publication Time Magazine:
http://time.com/2838438/the-two-germanys/

British publication The Economist:
http://www.economist.com/news/europe/21631130-fall-berlin-wall-closed-question-communism-it-reopened-question

silly billys

silly billies

What about hilly billies? Or billies goats?

HS2 nimbies

Ordinarily Din, also you'd spell it out, "two"
Maybe somebody will give us the exact rule

There isn't really a "rule", it's more a matter of style. You might write "2 pints of milk" in a shopping list but in an essay or other kind of serious work it is usual to write numbers out in full.