[Ifeffit] Athena .dat file

Hi, I worked on some data and I aligned them properly before to do any comparison. I also checked the alignment by plotting all the data together. After that I exported the data to have a file usable on Origin (the .dat format) but the problem is that after plotting the data on Origin, they are not aligned anymore. Specifically one group of data is not aligned to the others. Do you know what could be the problem? And how can I solve it? Many thanks, Fabio