I have found the answer to my own question. Apologies for disturbing you guys...... Here is Junipers view:
Note: Use default as the client name when you want to define a default tunnel client. The default client enables the authentication of multiple LACs with the same secret and L2TP attributes. This behavior is useful when, for example, many new LACs are added to the network, because it enables the LACs to be used without additional LNS profile configuration.
Use default only on MX Series routers. The equivalent client name on M Series routers is *.