Thank you Craige.
It is JMP version 15.1.0 on Win 10.
I used mouse.
I created a new column with the "Numeric" data type and "Continuous" modeling type. Then I copied the column (with the same column properties) by selecting the whole column and clicking the "Edit"-"Copy with column names". Next I left clicked the new column head to select the column and pasted by choosing "Edit"-"Paste with column names".
I think the problem is tentatively solved because I tried to do it again on the other day and now I can copy and paste the column exactly what they are. I must miss something that day. The original data was copy-paste from the results of the formulated cells in the excel. I don't know whether the formular in the excel would have an influence on this.
Thanks again for your reply!