If you're talking about Sargatanas That is my FC Beholders of Animus who bought 2 plots of Land and it looks like its both in one FC but its not. We bought a Medium sized house with our Main FC and then made an Alternate FC with a very similar name, Same FC Crest, and same FC Tag <Anima> and purchased the Small house right below our Medium. Plots 29 & 26 in Mist, they both share a staircase so we thought it would be cool to have both.

We all worked hard to rank up this alt FC and to raise enough gil to purchase both plots. So to answer your question, no you can only own one plot of land per Free Company.