Why this matters
A single will can dispose of assets anywhere. The reason two documents are common is administrative rather than legal: the people who act on the Indian document are Indian banks, depositories, registrars and courts, and they work fastest with a short, India-specific will executed the way Indian law expects.
Splitting also decouples the timetables. The Indian estate does not have to wait for a US probate process to conclude, and vice versa.
What NRIs should consider
Scope each will explicitly
One says it deals with assets situated in India; the other says it deals with assets outside India. No asset appears in both.
Limit the revocation clause
The India will should revoke only earlier wills dealing with Indian assets and state that it does not revoke wills dealing with assets elsewhere. Ask your US attorney to mirror that.
Separate executors
Name someone who can act in each country, plus an alternate in each document.
Keep both in sync
When you update one, re-read the other. Changes of marriage, birth or property should prompt a review of both.
Get advice for complex estates
Trusts, US estate tax exposure, ancestral property or an existing family dispute all justify a cross-border estate attorney.
When professional legal advice may be appropriate
Consider speaking with a lawyer qualified in India if your estate spans several countries in a complicated way, if significant tax planning is involved, if a family dispute or contested estate is likely, if a business, trust or unusual ownership structure is part of the estate, or if you are unsure how a Will made where you live interacts with one covering Indian assets.