Export clip with original 5 fps

Using Premiere Pro, I am making short videoclips from longer videos recorded at 5 fps. 5 fps is used for technical reasons and is adequate for the purpose. I want the clips to have identical quality and fps as the input, i.e. no re-encoding, just copying the relevant frames. However, in the export tab, Premier won't let me choose lower fps than 10. I can't see any good reason for such a limitation. The resulting exported video indeed has an fps = 10 in the metadata tag. However, duration is correct, not half as long as expected if playback speed was doubled by doubling fps. Playback of the exported video also seems correct. This indicates either a doubling of the framecount by interlacing, wich I doubt, or rather an erroneous mismatch between fps tag and real fps (bug). This is very unfortunate, because the consequences for later use of the video clips in various programs are unknow, since I do not know if the eronous tag will be used.