Hello Nilesh,
load balancing is flow based also on an MPLS network.
Load balancing criteria of MPLS frames is based on internal MPLS label (VPN label) for MPLS L3 VPN service.
In any case, whatever is the type of MPLS service there will not be out of order issues as load balancing will be flow based and packets belonging to the same flow will be switched over the same path
Hope to help
Giuseppe