When I do a simple Drag and drop of a worksheet the list of validation value
remain the same but when the copy is made in VBA (ActiveSheet.copy
After:=ActiveSheet) then the list of validation is change from
(0,25;0,50;0,75;1,00) to (0;25;0;5;0;75;1;0).

I have tried to change the regional settings, and when doing so the list of
value remain the same. But I cannot change the settings of all the users who
are going to use the Workbook.

I have tried to temporarely change the UseSystemSeparators of the
application but to no avail.

Is there a way prevent this modification from happening?

Finaly, I have used a nested if in a personnalised validation. The formula is
something like this

=If(A1=0,25;True;If(A1=0,5;True;If(A1=0,75;True;If (A1=1;True;False))))

I don't like this solution because it does not adress the real problem, but
at the least it work. And then I wonder why the problem is there when I use a
list but not with the personnalized validation. It probably have to do with
the fact that in each case the copy function does not work the same way and
even then there is a diiference in the way a formula and a list are treated
by the copy function.