As Keith says, there is a rule in the CL General Section about only two clips per line. But this is a Contest rule, not a safety code issue.
If you can make a set of lines with two clips and four terminations (counting leadouts, lines, and handle), you could make a setup with four, six, or ten terminations and/or clips and be no less safe.
The only sense I could ever see behind the "two clip" rule was to preclude sneaking out some line length in a speed event.
On the practical side, back in the olden days some of the younger modelers tried to salvage broken lines by reterminating them and clipping the pieces together. In every case, the mass and drag of the extra connections (while it did not break) was unacceptable for any enjoyable flying.