Siddi people are Bantu people. They are not from Ethiopia or the Horn of Africa.
It's more plausible that some of the Mukrani families in Pakistan have Ethiopian ancestry but most of the Africans are probably not from Ethiopia but from all places of Africa. Ethiopia is really diverse. Every African country is. You have quite a lot of ethnic groups in Ethiopia that differ in looks, history etc. and are inhabiting different geographic regions of Ethiopia.
Makranis are different than siddis of india.. both in their appearance,facial features and even their complexion.. one factor might be asymmetrical mating patterns between African women and autochthonous males during the process of genetic admixture... but here is what these guys say:
Haplogroup U9 is a rare clade in mtDNA phylogeny, characterized only
recently in a few populations of Pakistan (
Quintana-Murci et al. 2004). Its
presence in Ethiopia and Yemen, together with some Indian-specific M
lineages in the Yemeni sample, points to gene flow along the coast of the
Arabian Sea. Haplogroups U9 and U4 share two common mutations at the
root of their phylogeny (
fig. 2B). It is interesting that, in Pakistan, U9
occurs frequently only among the so-called “negroid Makrani” population.
In this particular population, lineages specific to sub-Saharan Africans
occur as frequently as 39%, which suggests that U9 lineages in Pakistan
may have an African origin (Quintana-Murci et al. 2004). Regardless of
which coast of the Arabian Sea may have been the origin of U9, its
Ethiopian–southern Arabian–Indus Basin distribution hints that its
diversification from U4 may have occurred in regions far away from the
current area of the highest diversity and frequency of haplogroup U4—
East Europe and western Siberia.
Ethiopian Mitochondrial DNA Heritage: Tracking Gene Flow Across and Around the Gate of Tears
Am J Hum Genet. 2004 November; 75(5): 752–770.
http://thenile.phpbb-host.com/sutra4610.php
A few examples of Makranis :