const result = Array.from(this.item.reduce((m, t) => m.set(t.name, t), new Map()).values());
<option *ngFor="let i of taxlist | unique" [value]="i.tax_name {{i.tax_name}} ( {{i.tax_percentage}}% )</option>
this.InstructionTypes = val.filter((item, i, arr) =>
// filter by what prop you want, here we use certification
arr.findIndex((x) => x.entityTable === item.entityTable) === i);