A 2 in 1 ?

I have these 2 plants growing together.
I know that the one on the right is a Mangosteen

(Garcinia mangostana) - same genus such as the button mangosteen (G. prainiana) or the charichuelo (G. madruno).

whereas from the aroma i get after crushing one of it's leaves, the one on the left appears to be a Jambul 

(Syzygium cumini) - flowering plant family Myrtaceae.

At the time of procuring the mangosteen sapling some years ago, i do not recall whether the same was grafted onto this Jambul.

I am aware that in the case of grafts one is supposed to sever the "mother" plant off from the piggy back riding plant so that the former may not "overcome" the latter.

I realise i should have taken the picture from another angle clearly showing both the plants at the base. However, when viewed from another angle both the trunks of the plant appear to separately go into the earth but i suppose i should dig into the earth somewhat deeper to see if in fact this is a graft or simply 2 plants growing very close to each other.

Both the plants are almost 6 feet tall now and regularly giving out fresh leaves, individually

My concern is the Mangosteen.

I would very much like to nurture the Mangosteen into a full grown tree but everyone at home also loves the Jambul berry.

I suppose the best course for me to follow would be to excavate around the base and see whats going on down there and proceed on to take further remedial steps accordingly.

Whatever the findings, my fervent hope is that i shall be able to save/have both these beautiful trees.

Cheers.

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