Can I christen my son twice in two different countries?my son was christen in slovakia and I want to do it again in england with his younger sister.

Yes you can. Talk with the priest or minister of the church you are wanting to attend. If, for some reason they won't since it isn't necessary, you could certainly have a blessing.

can i christen my son twice in two different countries?my son was christen in slovakia and i want to do it again in england with his younger sister.

Christen as in to Baptize? If you are Catholic, no. You will be required to attend classes which instruct you in bringing up a Christian child.

Christen as in to bless. If you are Catholic , sure. As many times as you want. All you need do is ask a Priest to bless your child.

If you are not Catholic, I don't know.

maria138,
Most denominations that I am aware of baptize children or adults in that denomination only once.
However, some think that being baptized by another denomination in not valid. In that case they will baptize a person again in that particular faith.
So it depends on in what denomination your child was baptized in.
Peace and kindness,
Fred