Yes you can have.
See the following verse which i have used in this answer:
MadhuluvedhA yathA bhringah pushpAt pushAntaram vrajet |
JyAna luvdha stathA shishyah guro gurvantara vrajet ||
Just like the bee, desirous of honey, moves from one flower to the other, a disciple, desirous of knowledge, can likewise move from one Guru to another.
Kularnava Tantram 13.132
Also from the Uddava Gita we get the following verse:
na hy ekasmäd guror jïänaà su-sthiraà syät su-puñkalam
brahmaitad advitéyaà vai géyate bahudharñibhiù ||
Although God is one, sages have described Him in different manners. For this reason, one may not be able to gain a complete understanding of God from one ordinary spiritual master.
So, in such cases looking for more than one Guru is recommended. Lord Shiva, in that KulArnava verse i have given, is alluding exactly to such a scenario.
Bhrighu, Swetaketu had more than one Guru, for example.
Also, from this answer you can know that Sri RAmakrishna Paramhamsa had more than one Mantra Gurus. First, he was initiated by Sri KenArAm BhattachArya. And, then sometime later, he was further initiated by his female Guru Sri Bhairavi.
So, it is certainly allowed.
As regards, superiority, then that is not based on who initiated you first but rather on which DikshA uplifted your spiritual level more.
If after a DikshA you feel completely satisfied, then that Guru is the ultimate Guru for you.