<font-awesome-icon icon="fa-duotone fa-6" />
<FontAwesomeIcon icon="fa-duotone fa-6" />
.my-icon {
position: relative;
font: var(--fa-font-duotone);
font-style: normal;
}
.my-icon:before {
position: absolute;
content: "\36";
opacity:0.5
}
.my-icon:after {
content: "\36\36";
}
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 320 512" style="width: 30px;height: 30px;fill: black">
<path d="M167.7 160.8l64.65-76.06c11.47-13.45 9.812-33.66-3.656-45.09C222.7 34.51 215.3 32.01 208 32.01c-9.062 0-18.06 3.833-24.38 11.29C38.07 214.5 0 245.5 0 320c0 88.22 71.78 160 160 160s160-71.78 160-160C320 234.4 252.3 164.9 167.7 160.8zM160 416c-52.94 0-96-43.06-96-96s43.06-95.1 96-95.1s96 43.06 96 95.1S212.9 416 160 416z"/>
<path style="opacity: 0.5" d=""/>
</svg>
<i class="fa-duotone fa-6"></i>