Are both of these fences made by Lego? I have a group of 1 x 4 x 2 fences (Lego part 3633) in black, light bluish gray, and yellow.

However only a few of them say "Lego" on the bottom. These have hollow bottom pins (see picture below, right side).  The others do not say Lego or have a part number. They have solid bottom pins (see picture below, left side).

Normally I can feel the difference between Lego and non-Lego parts. But the parts with the solid pins have a Lego feel. Also the yellow ones are the same shade of yellow as my Legos and not the shade of MegaBloks I have.

Is it possible these solid pin fences are really Lego? Or have I been fooled?
I've got some of the left-hand side version with the solid pins and no markings in red.
They are most definitely original Lego as I never owned any non-Lego parts.
I'm fairly certain they came with the 1978 firetruck set nr. 620.