Each CzmlDataSource represents a single CZML document and should contain a single “document” packet with optional clock and each entity must have a unique id (or no id in which case Cesium will supply one. Your CZML string looks like two documents, but is treated as one. This causes the first instances of point and path to be replaced by the second.
Each of the entities in the example has a unique id: redLine, blueLine, orangeLine, purpleLine, and dashedLine. Both or your “line” entities have the id “path”. Likewise, your “point” entities have the id “point”.