Self doubt on SSA

Question

Convert the following 3 address code to single Static Assignment.

a = b + c

d = d + a.

Comments

its already in SSA:

For valid SSA , variables on lhs must be distinct

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Can you please explain the second instruction.

Is accessing does not consider for new variable assignment?

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While converting from 3address to ssa,   temporary variables are added when multiple assignments to a single variable are performed. What's wrong if same variable is read and written in same instruction ?