Lots of chanotes around like this. Two reasons. First is that plots are often handed down and split up for the kids. Second is that they sometime do not request seperate chanotes because they are tight fisted and also assume the land will remain in the family for ever.
What you do need to check closely is that the four digit number on each of the whooa chanote (cement pegs) is the same as the number printed on the chanote.
It also looks like there is some kind of easement across the front (or it might be the back) of the block you want to buy. Best check that out in detail also.
Also take care to note that most land offices have a long wait time for issuing chanotes, pegging, or checking, boundaries....think 6 months or more. You might be able to arrange express service with a bribe.